using System;

public class Program

{

    public static void Main()

    {

        int[] arr = { 1, 5, 23, 1, 5, 23, 1, 5, 23, 87, 1, 5, 23, 1, 5, 23, 1, 5, 66 };

        GetHashCode(arr).Dump();

    }

    static int GetHashCode(int[] values)

    {

       int result = 0;

       int shift = 0;

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

       {

          shift = (shift + 8) % 21;

          result ^= (values[i]) << shift;

       }

       return result;

    }

}