题解 | #判断字母#

import java.util.Scanner;
public class Main {
    
    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        String str = sc.next();
        int c = (int)str.charAt(0);
        if(c >= 65 && c <= 90) {
            System.out.println("YES");
        } else if(c >= 97 && c <= 122) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}