using System;

public static class Program

{

    // generates a random long in the range [1, long.MaxValue]

    public static long randomPositiveLong(Random r)

    {

        return (r.Next(0, int.MaxValue) + 1) // bits 0 to 30 (least significant)

            + ((r.Next(-1, int.MaxValue) + 1) << 31) // bits 31 to 61

            + (r.Next(0, 2) == 0 ? (long)1 << 62 : 0); // bit 62 (most significant, because bit 63 is the sign bit)

    }

    public static void Main()

    {

        int abilities = 3000;

        long[] ids = new long[abilities];

        long seed = (long)(DateTime.UtcNow - new DateTime(2021, 2, 2, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds;

        Console.WriteLine(seed.ToString());

        Random r = new Random((int)seed);

        bool match = false;

        int matches = 0;

        for (int k = 0; k < 100; k++)

        {

            for (int i = 0; i < ids.Length; i++)

            {

                //long lo = randomPositiveLong(r);

                long lo = r.Next(0, 10000000);

                match = false;

                for (int j = 0; j < i; j++)

                {

                    if (lo == ids[j])

                    {

                        match = true;

                        break;

                    }

                }

​

                if (match)

                {

                    matches++;

                    break;

                }

                else

                {

                    ids[i] = lo;

                }

            }

        }

        Console.WriteLine(matches);

    }

}