题解 | #判断字母#

import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        while(scan.hasNextLine()){//读一行输出一行
            String str = scan.nextLine();
            char ch = str.charAt(0);//先将str转化为字符
            boolean bool = Character.isLetter(ch);//之后判断是否为字母
            String result = bool ? "YES" : "NO";//最后将true和false转为YES和NO
            System.out.println(result);
        }
        
    }
}