14.ExchangeBits

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        uint n = 4290772963;

        //Print the number before it has been changed for comparison
        Console.WriteLine(Convert.ToString(n, 2));

        byte p = 3;
        byte q = 2;
        byte k = 21;
        uint mask = 1;//when shifting right you need yout right side to be int

        //set the mask E.g (2^3) - 1
        for (int i = 0; i < p; i++)
        {
            mask *= 2;
        }

        //get the first bits
        uint getFirstBits = (((mask - 1) << q) & n) >> q;
        //get the second bits
        uint getSecondBits = (((mask - 1) << k) & n) >> k;

        //null the first bits
        n = n & (~((mask - 1) << q));
        //null the second bits
        n = n & (~((mask - 1) << k));

        //we concatnate the first bits and the nulled number(we exchange them)
        n = n | (getFirstBits << k);

        //we concatnate the second bits and the nulled number(we exchange them)
        n = n | (getSecondBits << q);

        //Print changed
        Console.WriteLine(Convert.ToString(n, 2));
    }
}