wordle

Problem
Chef invented a modified wordle.
There is a hidden word S and a guess word T, both of length 5.
Chef defines a string M to determine the correctness of the guess word. For the ℎi th
index:
If the guess at the ℎi th index is correct, the ℎi th character of M is G.
If the guess at the ℎi th index is wrong, the ℎi th character of M is B.
Given the hidden word S and guess T, determine string M.

/* 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();
		for(int i=0;i<t;i++)
		{
		    String a=sc.next();
		    String b=sc.next();
		    String c=" ";
		    
		    for(int j=0;j<5;j++)
		    {
		        if(a.charAt(j)==b.charAt(j))
		        {
		            c=c+"G";
		        }
		        else
		        {
		            c=c+"B";
		        }
		    }
		    System.out.println(c);
		}// your code goes here
	}
}