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.Text;
using System.Threading.Tasks;
 
namespace ConsoleApp2
{
    class Program
    {
        static void Main()
        {
            var a = int.Parse(Console.ReadLine());
            var ans = string.Empty;
            ans = ToColumnName((a - 1) / 26) + (char)('a' + ((a - 1) % 26));
 
            Console.WriteLine(ans);
        }
        public static string ToColumnName(int source)
        {
            if (source < 1) return string.Empty;
            return ToColumnName((source - 1) / 26) + (char)('a' + ((source - 1) % 26));
        }
    }
}