#include <bits/stdc++.h>
using namespace std;
int main()
{
	char s[10005];
	while(cin>>s){
		stack<char> st;
		for(int i=0; i<strlen(s); i++){
			if(!st.empty()){
				char c=st.top();
				if(c=='<'&&s[i]=='>' || c=='('&&s[i]==')' || c=='['&&s[i]==']'||c=='{'&&s[i]=='}')
					st.pop();
				else st.push(s[i]);
			}else st.push(s[i]);
		}
		if(st.empty()) cout<<"yes"<<endl;
		else cout<<"no"<<endl;
	}
}