Hackerrank Java堆栈代码中的运行时错误

Question

在hackerrank java堆栈问题中，我已经设计了代码，但是它没有给出正确的输出，并且在测试用例中给出了运行时错误

import java.util.*;

class Solution {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            String input = sc.next();
            System.out.println(isBalanced(sc.next()));
        }

        sc.close();
    }

    static boolean isBalanced(String parantheses) {
        Stack < Character > stack = new Stack < Character > ();
        for (int i = 0; i < parantheses.length(); i++) {
            char ch = parantheses.charAt(i);
            if (ch == '(' || ch == '{' || ch == '[') {
                stack.push(ch);

            } else if (stack.empty()) {
                return false;
            } else {
                char top = stack.pop();
                if ((top == '(' && ch != ')') || (top == '[' && ch != ']') || (top == '{' && ch != '}')) {
                    return false;
                }
            }
        }
        return stack.empty();
    }
}