#include<bits/stdc++.h>
using namespace std;
char c;
stack <int> mystack;
int main()
{
	while(~scanf("%c",&c))
	{
		if(c=='(')
		{
			mystack.push(c);
		}
		if(c==')')
		{
			mystack.pop();
		}
		
		
		if(c=='@')
		{
		if(mystack.size()==0)
		{
			cout<<"YES";
		}
		if(mystack.size()!=0)
		{
			cout<<"NO";
		}
		}
		
		
	}
	return 0;
}