Substitute C#

using System;

class Program
{
    static void Main(string[] args)
    {
        int k = int.Parse(Console.ReadLine());
        int l = int.Parse(Console.ReadLine());
        int m = int.Parse(Console.ReadLine());
        int n = int.Parse(Console.ReadLine());
        int changeCount = 0;

        for (int first = k; first <= 8; first++)
        {
            for (int second = 9; second >= l; second--)
            {
                for (int third = m; third <= 8; third++)
                {
                    for (int fourth = 9; fourth >= n; fourth--)
                    {
                        if (first % 2 == 0 && second % 2 != 0 && third % 2 == 0 && fourth % 2 != 0)
                        {
                            if (first == third && second == fourth)
                            {
                                Console.WriteLine("Cannot change the same player.");
                            }
                            else
                            {
                                Console.WriteLine($"{first}{second} - {third}{fourth}");
                                changeCount++;
                            }

                            if (changeCount >= 6)
                            {
                                Environment.Exit(0);
                            }
                        }
                    }
                }
            }
        }
    }
}