Here is my code..

The program always return YES value. I don't know why?

// I have pasted down the question link below.

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
 
public class Solution {
 
    static String isBalanced(String s) {
        // Complete this function
        Stack<String> stack=new Stack<>();
        int q=s.length()-1;
        int i=0;
        while(i<=q)
        {
            String p=""+s.charAt(i);
            if(p=="{"){
                stack.push(p);}
            if(p=="("){
                stack.push(p);}
            if(p=="["){
                stack.push(p);}
           if((p=="}" && (stack.peek()=="{")) || (p==")" && (stack.peek()=="(")) || (p=="]" && (stack.peek()=="["))){
                stack.pop();}
            i++;
        }
       if(stack.empty())
        return "YES";
        else
        return "NO";
    }
 
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int t = in.nextInt();
        for(int a0 = 0; a0 < t; a0++){
            String s = in.next();
            String result = isBalanced(s);
            System.out.println(result);
        }
        in.close();
    }
}