[백준] 3986번 좋은 단어 [JAVA]

package ps;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.Stack;

public class BOJ_3986 {

	
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        
        int N = Integer.parseInt(br.readLine());
        
        
        int count = 0;
        
        for(int i=0;i<N;i++) {
        	String word = br.readLine();
        	Stack<Character> s = new Stack<>();
        	
        	for(char c : word.toCharArray()) {
        		
        		if(s.size() == 0 ) {
        			s.push(c);
        			continue;
        		}
        		else {
        			if(s.peek() == c) {
        				s.pop();
        				continue;
        			}
        			else {
        				s.push(c);
        			}
        		}
        	}
        	if(s.size() == 0 ) {
        		count++;
        	}
        }
        
        System.out.println(count);
	}
}