#include <iostream>
#include <unordered_map>
#include <stack>

using namespace std;

unordered_map<char, int> mp{
        {'(', -1},
        {')', 1},
        {'{', -2},
        {'}', 2},
        {'[', -3},
        {']', 3},
        {'<', -4},
        {'>', 4}
};
int main()
{
    stack<char> op;
    string s;
    cin >> s;

    bool c = true;
    for(int i = 0; i < s.size(); i ++)
    {
        int t = mp[s[i]];
        if(t < 0)
            op.push(t);
        else
        {
            if(op.size() && op.top() == -t)//首先判断栈是否有元素
                op.pop();
            else
            {
                c = false;
                break;
            }
        }
    }

    if(op.size()) c = false;

    if(c)   cout << "yes" << endl;
    else cout << "no" << endl;

    return 0;
}