51

import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws FileNotFoundException {
//        Scanner scanner = new Scanner(System.in);
        Scanner in = new Scanner(new File("input.txt"));
        PrintWriter pw = new PrintWriter("output.txt");


        Stack<Character> stack = new Stack<>();
        String a = in.next();

        boolean flag = false;
        for (int i = 0; i < a.length(); i++)
            if (a.charAt(i) == '{' || a.charAt(i) == '(' || a.charAt(i) == '[') stack.push(a.charAt(i));
            else if (stack.size() == 0) flag = true;
            else if (stack.peek() == '{' && a.charAt(i) == '}' || stack.peek() == '(' && a.charAt(i) == ')' || stack.peek() == '[' && a.charAt(i) == ']')
                stack.pop();
            else flag = true;


        if (stack.size() != 0) flag = true;

        if (flag) {
            pw.println("no");
        } else {
            pw.println("yes");
        }


        in.close();
        pw.close();


    }
}