题解

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