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| − | {{stub}}
| + | #REDIRECT [[Codesize#Common_Tricks]] |
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| − | <div style="background-color:#060; font-size:1px; height:8px; border:1px solid #AAAAAA; -moz-border-radius-topright:0.5em; -moz-border-radius-topleft:0.5em;"></div>
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| − | <div style="background-color:#FFFFFF;border:1px solid #AAAAAA; border-top:0px solid white; padding:5px 5px 0 5px; margin-bottom:3ex">
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| − | <center>
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| − | <big style="color: #000; display: block; background: #cfc; border:solid 1px #060;padding: 0.3em;">'''Code Size Cheat sheet'''</big>
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| − | | |
| − | {| style="width: 100%; vertical-align:top;"
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| − | | style="width: 60%; vertical-align:top; border-right: 1px solid #aaa" |
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| − | {| width="100%" cellpadding="2" cellspacing="5" style="vertical-align:top;"
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| − | | style="margin:0; background:#e0efef; border:1px solid #a3bfb1; font-weight: bold; text-align:left; color:#000; padding:0.1em 0.4em;" | Do and Don't
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| − | |-
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| − | {| width="100%"
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| − | |style="text-align:center;font-weight:bold;width:50%"| Do ||style="text-align:center;font-weight:bold;width:50%"| Don't
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| − | |-
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| − | |style="padding: 0"|
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| − | <syntaxhighlight>
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| − | class Robot
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| − | extends AdvancedRobot
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| − | {
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| − | static double varname;
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| − | public void run() {
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| − | LinkedList list;
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| − | try{
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| − | someFunction
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| − | (list.getFirst());
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| − | } catch(Exception ex){}
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| − | | |
| − | int i = 1;
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| − | if (j > 2) {
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| − | i = -1;
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| − | }
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| − | | |
| − | }
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| − | public void
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| − | onScannedRobot
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| − | (ScannedRobotEvent e)
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| − | double a;
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| − | double t = getEnergy()
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| − | * (a = e.getBearing());
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| − | }
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| − | }
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| − | </syntaxhighlight>
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| − | |
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| − | <syntaxhighlight>
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| − | class Robot
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| − | extends AdvancedRobot
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| − | {
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| − | double varname = 0;
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| − | public void run() {
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| − | | |
| − | LinkedList list;
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| − | if(list.size() != 0){
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| − | someFunction
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| − | (list.getFirst());
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| − | }
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| − | | |
| − | int i;
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| − | if (j > 2) {
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| − | i = -1;
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| − | } else {
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| − | i = 1;
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| − | }
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| − | }
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| − | | |
| − | public void
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| − | onScannedRobot
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| − | (ScannedRobotEvent e)
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| − | double a = e.getBearing();
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| − | double t = a * getEnergy();
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| − | | |
| − | }
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| − | }
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| − | </syntaxhighlight>
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| − | <!--
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| − | The code is very ugly, agree?
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| − | | |
| − | Because I can't fit it in remaining 30% of full table. Please help me manage this page if you can.
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| − | -->
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| − | |}
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| − | |-
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| − | | style="margin:0; background:#e0efef; border:1px solid #a3bfb1; font-weight: bold; text-align:left; color:#000; padding:0.1em 0.4em;" | A magic of register
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| − | |-
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| − | |style="text-align:justify"|
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| − | Every operation to anything must be done from register. Java has 4 registers to hold variable. If the method is not static, the first one is <code>this</code> reference. The remaining registers will be use for each parameter and variable inside method. Every type of variable use 1 register, except double use 2. When 3 registers are already used by other variable, a double value will then be assigned an extra register (and the codesize is as if there was only 1 used). If you do any operation on any variable that is not on the register, Java will need to move that variable to the register before doing any of your operation, which costs codesize. This mean you should define most-used variables before any other variables.
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| − | | |
| − | Do this:
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| − | <syntaxhighlight>
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| − | public void onScannedRobot(ScannedRobotEvent e) {
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| − | int int_variable_if_you_want;
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| − | double bearing =
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| − | e.getBearingRadians() + getHadingRadians();
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| − | double distance = e.getDistance();
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| − | // ...
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| − | }
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| − | </syntaxhighlight>
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| − | Don't do this:
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| − | <syntaxhighlight>
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| − | public void onScannedRobot(ScannedRobotEvent e) {
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| − | double distance = e.getDistance();
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| − | int int_variable_if_you_want;
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| − | double bearing =
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| − | e.getBearingRadians() + getHadingRadians();
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| − | // ...
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| − | }
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| − | </syntaxhighlight>
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| − | | |
| − | |-
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| − | | style="margin:0; background:#e0efef; border:1px solid #a3bfb1; font-weight: bold; text-align:left; color:#000; padding:0.1em 0.4em;" | Loop with while
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| − | |-
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| − | |style="text-align:justify"|
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| − | You should always end up with less code size if you switch your for{each}( ...) loops to while loops. This applies to Lists as well to Arrays, just put an try..catch.. around the while to save the null, zero or "array out of bound" check.
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| − | | |
| − | Do this:
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| − | <syntaxhighlight>
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| − | public void onScannedRobot(ScannedRobotEvent e) {
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| − | try {
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| − | Iterator<your_class> iter = yourList.iterator();
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| − | while(true) {
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| − | your_class obj = iter.next();
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| − | ...... // your code
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| − | }
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| − | } catch (Exception e) {}
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| − | | |
| − | }
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| − | </syntaxhighlight>
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| − | | |
| − | Don't do this: (8 byte more)
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| − | <syntaxhighlight>
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| − | public void onScannedRobot(ScannedRobotEvent e) {
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| − | foreach(your_class obj: yourList) {
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| − | ...... // your code
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| − | }
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| − | }
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| − | </syntaxhighlight>
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| − | | |
| − | | |
| − | |}
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| − | | style="width: 40%; vertical-align:top;" |
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| − | {| cellpadding="2" cellspacing="5" style="width: 100% vertical-align:top;"
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| − | | style="margin:0; background:#e0efef; border:1px solid #a3bfb1; font-weight: bold; text-align:left; color:#000; padding:0.1em 0.4em;" | Cost
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| − | |-
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| − | |
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| − | {|
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| − | | '''Operation''' ||style="text-align:right"| '''Cost in bytes'''
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| − | |-
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| − | | creating a class ||style="text-align:right"| 5
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| − | |-
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| − | | 1st constructor ||style="text-align:right"| free
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| − | |-
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| − | | creating a method ||style="text-align:right"| free
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| − | |-
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| − | | returning from a method ||style="text-align:right"| 1
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| − | |-
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| − | | calling a method ||style="text-align:right"| 3
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| − | |-
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| − | | storing a local (non-register) variable ||style="text-align:right"| 1
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| − | |-
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| − | | loading a local (non-register) variable ||style="text-align:right"| 1
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| − | |-
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| − | | storing a static variable ||style="text-align:right"| 2
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| − | |-
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| − | | loading a static variable ||style="text-align:right"| 2
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| − | |-
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| − | | loading integer literals -1 to 5 ||style="text-align:right"| 1
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| − | |-
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| − | | loading integer literals -128 to 127 ||style="text-align:right"| 2
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| − | |-
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| − | | loading integer literals -32768 to 32767 ||style="text-align:right"| 3
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| − | |-
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| − | | loading other integer literals ||style="text-align:right"| 2
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| − | |-
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| − | | loading double literals 0, 1 ||style="text-align:right"| 1
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| − | |-
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| − | | loading double literals -1, 2, 3, 4, 5 ||style="text-align:right"| 2
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| − | |-
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| − | | loading other double literals ||style="text-align:right"| 3
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| − | |-
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| − | | loading string literals ||style="text-align:right"| 2
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| − | |-
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| − | | declaring a variable ||style="text-align:right"| free
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| − | |-
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| − | | casting ||style="text-align:right"| 1
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| − | |-
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| − | | promotion ||style="text-align:right"| 1
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| − | |-
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| − | | arithmetic ||style="text-align:right"| 1
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| − | |-
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| − | | ++ and -- (register or not) ||style="text-align:right"| 1
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| − | |}
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| − | |}
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| − | |}
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| − | | |
| − | </center>
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| − | </div>
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