#include <iostream>
#include <stack>
using namespace std;

int main() {
    char s;
    stack<char> ourstack;
    while (cin >> s && s != '#') {
        if (s == '(' || s == '{' || s == '[') {
            ourstack.push(s);
        } else if (s == ')' && ourstack.top() == '(') {
            ourstack.pop();
        }  else if (s == '}' && ourstack.top() == '{') {
            ourstack.pop();
        }  else if (s == ']' && ourstack.top() == '[') {
            ourstack.pop();
        } else { cout << "no"; return 0;}

    }
    if (!ourstack.empty()) {
        cout << "no";
    } else {
        cout << "yes";
    }
    return 0;
}