/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
 
		System.out.println(getDifferIndex(new int[]{0,1,2}, new int[]{0,1,2,3}));
 
	}
 
	public static int getDifferIndex(int[] a, int[] b) {
		int i = 0;
		while (i < a.length && i < b.length && a[i] == b[i++]);
		return i;
	}
}

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