bruh what happend to hankerrank it feels like a cheap website it wasn't like this before the code isn't working

import java.io.; import java.util.;

public class Solution {

public static void main(String[] args) {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
    Scanner sc = new Scanner(System.in);
    String str = sc.next();
    String str2 = sc.next();

    String result = xor(str, str2);
    System.out.println(result);

}

public static String xor(String str, String str2)
{
    StringBuilder s = new StringBuilder();
    for(int i = 0; i <= str.length() - 1; i+=1)
    {
        int num1 = str.charAt(i) - '0';
        int num2 = str2.charAt(i) - '0';
        s.append(num1 ^ num2);
    }
    return s.toString();
}

}