Help me in solving SINGLEOP1 problem

help
,
1

My issue

I dont know what to do. Please help.

My code

/* package codechef; // 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 Codechef
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner sc = new Scanner(System.in);
		int t = sc.nextInt();
		
		while(t --> 0){
		    int N = sc.nextInt();
		    String S = sc.next();
		    
		    int value = Integer.parseInt(S, 2);
		    
		  //  System.out.println(value);
		    int max = 0, index = 0;
		    for(int i=1;i<=N;i++){
		        int X = value ^ (value/(1 << i));
		      //  System.out.print(X+" ");
		        if (X > max){
		            max = X;
		            index = i;
		        }
		        
		    }
		    System.out.println(index);
		}
	}
}

Problem Link: SINGLEOP1 Problem - CodeChef