#include<bits/stdc++.h>
//#include<windows.h>
using namespace std;
int main(){
	int cds;
	char k;
	do{
		cin>>k;
		if(k=='('){
			cds++;
		}else{
			if(k==')'){
				cds--;
			}
		}
		if(k=='@'){
			if(cds!=0){
				cout<<"NO";
			}else{
				cout<<"YES";
			}
		}
	}while(k!='@');
	
	return 0;
}

本机测试没问题啊，怎么到了评测机上就WA了呢