C :

#include <stdio.h>
main() {
    char c;int t=0;
    while ((c=getchar())!='@') {
        if(c=='(')t++;
		if(c==')'){
			t--;
			if(t<0)break;
		}	
    }
    if (t==0) printf("YES");
    	else printf("NO");	
} 

C++ :

#include<iostream>
#include<cstring>
#include<cstdio>
#include<stack>
using namespace std;
string s;
stack<char> a;
bool my_judge(string);
int main()
{	
	cin>>s;
	if(my_judge(s))cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
	return 0;
}
bool my_judge(string s)
{
	int i=0;
	while(s[i]!='@')
	{
		if(s[i]=='(')a.push(s[i]);
		if(s[i]==')')
		{
			if(a.empty()) return false;
			a.pop();
		}
		i++;
	}
	if(a.empty())return true;
	else return false;
}