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: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AtCoder.Abc
{
    // https://atcoder.jp/contests/abc171/tasks/abc171_a
    class A_171_αlphabet
    {
        public static void Main(string[] args)
        {
            var sw = new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);

            // 文字列の入力
            string s = Console.ReadLine();

            // 大文字の場合、「A」を表示
            if (System.Text.RegularExpressions.Regex.IsMatch(s, "[A-Z]"))
            {
                Console.WriteLine("A");
            }
            // 小文字の場合、「a」を表示
            else
            {
                Console.WriteLine("a");
            }

            Console.Out.Flush();
        }
    }
}