Codility #10. Nesting

import java.util.*;

class Solution {
    public int solution(String S) {
        int N = S.length();
        if(N == 0) {
            return 1;
        }
        Stack stack = new Stack();
        char temp;
        for(int i = 0; i < N; i++) {
            temp = S.charAt(i);
            if(temp == '(') {
                stack.push(temp);
            }else {
                if(stack.isEmpty()) {
                    return 0;
                }else {
                    stack.pop();
                }
            }
        }
        if(!stack.isEmpty()) {
            return 0;
        }else {
            return 1;
        }

    }
}