> #include <iostream>
> #include <iomanip>
> using namespace std;
> 
> int main()
> {
> 	int a,b,c,n;
> 	while(cin>>n)
> 	{
> 		if(n<2)	
> 		{
> 			while(n>=0)
> 			{
> 				n--;
> 				cin>>a;
> 			}
> 			cout<<"YES"<<endl;
> 		}
> 		else if(n==2)
> 		{
> 			cin>>a>>b>>c;
> 			if(b*b>=4*a*c)
> 				cout<<"NO"<<endl;
> 			else
> 				cout<<"YES"<<endl;
> 		}
> 		else
> 		{
> 			while(n>=0)
> 			{
> 				n--;
> 				cin>>a;
> 			}
> 			cout<<"NO"<<endl;
> 		}
> 	}
> 	return 0;
> }
> 
>