题解

#include<bits/stdc++.h>
using namespace std;
stack<char> st;
char c;
int main(){
	while(true){
		cin>>c;
		if(c=='@') break;
		else if(c=='(') st.push(c);
		else if(c==')'){
			if(st.empty()){
				cout<<"NO";
				return 0;
			}
			else st.pop();
		}
	}
	if(st.empty()) cout<<"YES";
	else cout<<"NO";
	return 0;
}