A solution without using stack -

import java.util.*; class Solution{

public static void main(String []argh)
{
    Scanner sc = new Scanner(System.in);

    while (sc.hasNext()) {
        String input=sc.next();
        int count = 0;
        //Complete the code
        if (input.length() % 2 == 0){
           for (int i = 0 ; i < input.length(); i++){
                if (input.charAt(i) == '{' ||
                    input.charAt(i) == '[' ||
                    input.charAt(i) == '('){
                    count+=1;
                }
                else{
                    count-=1;
                }
                if(count < 0){
                    System.out.println("false");
                    break;
                }
            } 
            if (count == 0){
                System.out.println("true");
            }
        }
        else {
            System.out.println("false");
        }

    }

}

}