15Numbers1To100ToText

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

namespace _15Numbers1To100ToText
{
    class Numbers1To100ToText
    {
        static void Main(string[] args)
        {
            int num = int.Parse(Console.ReadLine());
            if (num >= 0 && num < 20)
            {
                switch (num)
                {
                    case 0: Console.WriteLine("zero"); break;
                    case 1: Console.WriteLine("one"); break;
                    case 2: Console.WriteLine("two"); break;
                    case 3: Console.WriteLine("three"); break;
                    case 4: Console.WriteLine("four"); break;
                    case 5: Console.WriteLine("five"); break;
                    case 6: Console.WriteLine("six"); break;
                    case 7: Console.WriteLine("seven"); break;
                    case 8: Console.WriteLine("eight"); break;
                    case 9: Console.WriteLine("nine"); break;
                    case 10: Console.WriteLine("ten"); break;
                    case 11: Console.WriteLine("eleven"); break;
                    case 12: Console.WriteLine("twelve"); break;
                    case 13: Console.WriteLine("thirteen"); break;
                    case 14: Console.WriteLine("fourteen"); break;
                    case 15: Console.WriteLine("fifteen"); break;
                    case 16: Console.WriteLine("sixteen"); break;
                    case 17: Console.WriteLine("seventeen"); break;
                    case 18: Console.WriteLine("eighteen"); break;
                    case 19: Console.WriteLine("nineteen"); break;
                }
            }

            else if (num >= 20 && num < 100)
            {
                int first = num / 10;
                int second = num % 10;
                switch (first)
                {
                    case 1: Console.Write("ten"); break;
                    case 2: Console.Write("twenty"); break;
                    case 3: Console.Write("thirty"); break;
                    case 4: Console.Write("fourty"); break;
                    case 5: Console.Write("fifty"); break;
                    case 6: Console.Write("sixty"); break;
                    case 7: Console.Write("seventy"); break;
                    case 8: Console.Write("eighty"); break;
                    case 9: Console.Write("ninety"); break;
                }
                switch (second)
                {
                    case 1: Console.WriteLine(" one"); break;
                    case 2: Console.WriteLine(" two"); break;
                    case 3: Console.WriteLine(" three"); break;
                    case 4: Console.WriteLine(" four"); break;
                    case 5: Console.WriteLine(" five"); break;
                    case 6: Console.WriteLine(" six"); break;
                    case 7: Console.WriteLine(" seven"); break;
                    case 8: Console.WriteLine(" eight"); break;
                    case 9: Console.WriteLine(" nine"); break;
                    default:
                        break;
                }
            }
            else if(num == 100)
            {
              Console.WriteLine("one hundred");

            }

            else if(num < 0 || num > 100)
            {
                Console.WriteLine("invalid number");
            }
        }
    }
}