一直看不懂错哪了

#include<iostream>
#include<cstring> 
using namespace std;
int n;
char i;

int main(){
	do{
		i=getchar();
		if(i=='(') n+=1;
		if(i==')') n-=1;
		if(n<0) break;	
	}while(i=='@');
	if (n==0) cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
	return 0;}