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: Runtime Error)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices.ComTypes;

namespace AtCoder
{
    class Program
    {
        static void Main(string[] args)
        {
            double n = double.Parse(Console.ReadLine());

            string ans = null;

            while (n / 26 != 0)
            {
                ans = SetName(Math.Floor(n % 26)) + ans;
                n = Math.Floor(n / 26);
            }

            Console.WriteLine(ans);
        }

        static private string SetName(double num)
        {
            string alph = null;

            if (num == 1) alph = "a";
            else if (num == 2) alph = "b";
            else if (num == 3) alph = "c";
            else if (num == 4) alph = "d";
            else if (num == 5) alph = "e";
            else if (num == 6) alph = "f";
            else if (num == 7) alph = "g";
            else if (num == 8) alph = "h";
            else if (num == 9) alph = "i";
            else if (num == 10) alph = "j";
            else if (num == 11) alph = "k";
            else if (num == 12) alph = "l";
            else if (num == 13) alph = "m";
            else if (num == 14) alph = "n";
            else if (num == 15) alph = "o";
            else if (num == 16) alph = "p";
            else if (num == 17) alph = "q";
            else if (num == 18) alph = "r";
            else if (num == 19) alph = "s";
            else if (num == 20) alph = "t";
            else if (num == 21) alph = "u";
            else if (num == 22) alph = "v";
            else if (num == 23) alph = "w";
            else if (num == 24) alph = "x";
            else if (num == 25) alph = "y";
            else if (num == 0) alph = "z";

            return alph;
        }
    }
}