题解 | #判断字母#

#include<iostream>
#include<iomanip>

using namespace std;

int main()
{
	char c;

	while (cin >> c)
		if((c>='a'&&c<='z')||(c>='A'&&c<='Z'))
			std::cout << "YES" << endl;
		else
			std::cout << "NO" << endl;

	return 0;
}