#include <iostream>
#include <stack>

using namespace std;


int main() {
    char ch;
    stack<char> dict;
    int flag = 0;

    while (cin >> ch) {
        if (ch == '<' || ch == '(' || ch == '{' || ch == '[') {
            dict.push(ch);
        }
        else {
            if (!dict.empty()){
                if (ch == '>' && dict.top() == '<')  dict.pop();
                else if (ch == ')' && dict.top() == '(')  dict.pop();
                else if (ch == '}' && dict.top() == '{')  dict.pop();
                else if (ch == ']' && dict.top() == '[')  dict.pop();
                else break;
            }
            else{
                flag = 1;
                break;
            }
        }
    }
    if (!dict.empty() || flag) cout << "no" << endl;
    else cout << "yes" << endl;

    return 0;
}