Problem:
Score : 100 points

Problem Statement

An uppercase or lowercase English letter \alpha will be given as input.
If \alpha is uppercase, print A; if it is lowercase, print a.

Constraints

\alpha is an uppercase (A - Z) or lowercase (a - z) English letter.

Input

Input is given from Standard Input in the following format:

α

Output

If \alpha is uppercase, print A; if it is lowercase, print a.

Sample Input 1

B

Sample Output 1

A

B is uppercase, so we should print A.

Sample Input 2

a

Sample Output 2

a

a is lowercase, so we should print a.

Solution in C# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;
using System.Text;
using System.Collections.Generic;
using System.Linq;
using System.IO;

namespace AtCoder.A
{ 
    public class Program
    {
        public static void Main(string[] args)
        {
            var s = r();
			if (Char.IsUpper(s[0]))
			{
                P("A");
                return;
			}
            P("B");
        }

        private static StreamReader sr;
        public static int[] Ecr()
        {
            if (sr == null)
            {
                sr = new StreamReader("input.txt", Encoding.GetEncoding("UTF-8"));
            }
            return sr.ReadLine().Split().Select(int.Parse).ToArray();
        }
        public static string Er()
        {
            if (sr == null)
            {
                sr = new StreamReader("input.txt", Encoding.GetEncoding("UTF-8"));
            }
            return sr.ReadLine();
        }
        public static string r()
        {
            return Console.ReadLine();
        }
        public static  int[] cr()
        {
            return Console.ReadLine().Split().Select(int.Parse).ToArray();
        }
        public static int cri()
        {
            return int.Parse(Console.ReadLine());
        }
        public static void P(string str)
        {
            Console.WriteLine(str);
        }
        public static void P(int num)
        {
            P(num.ToString());
        }
    }
}