题解

#include<bits/stdc++.h>
using namespace std;
int main(){
    string s;
    cin>>s;
    int left=0,right=0;
    int idx=0;
    while(s[idx]!='@'){
		if(s[idx]=='('){
			left++;
		}
		if(s[idx]==')'){
			right++;
		}
		if(right>left){
			cout<<"NO";
			return 0;
		}
		idx++;		
	}
	if(left>right){
		cout<<"NO";
	}else{
		cout<<"YES";
	}
	return 0;
}