3.ExchangesBitsIn32Integer_AdvancedTask

using System;

class BitsExchange_AdvancedTask
{
    static void Main ()
    {
        checked
        {
            Console.Write("Please, enter a whole non-negative Integer number N = ");
            string numberStr = Console.ReadLine();
            int numberN = int.Parse(numberStr);
            Console.Write("Enter a whole number for a bit position in the range [0...30], P = ");
            numberStr = Console.ReadLine();
            int bitPositionP = int.Parse(numberStr);
            Console.Write("Enter other whole number for a bit position in the range [0...30], Q = ");
            numberStr = Console.ReadLine();
            int bitPositionQ = int.Parse(numberStr);
            Console.Write("Enter a whole number for a count of bit positions in the range [2...31], K = ");
            numberStr = Console.ReadLine();
            int countBitsK = int.Parse(numberStr);
            if ((bitPositionP + countBitsK) > 32 || (bitPositionQ + countBitsK) > 32)
            {
                Console.WriteLine("Error - Invalid Input !!!");
                Console.ReadLine();
                return;
            }

            // Get bits from the number
            int firstSequenceBits = 0;
            int secondSequenceBits = 0;
            for (int i = 0; i < countBitsK; i++)
            {
                if ((numberN & (1 << (bitPositionP + i))) != 0)
                {
                    firstSequenceBits |= (1 << i);
                }
                numberN &= ~(1 << (bitPositionP + i));

                if ((numberN & (1 << (bitPositionQ + i))) != 0)
                {
                    secondSequenceBits |= (1 << i);
                }
                numberN &= ~(1 << (bitPositionQ + i));
            }

            // Exchange the bits
            numberN |= secondSequenceBits << bitPositionP;
            numberN |= firstSequenceBits << bitPositionQ;

            // Print result
            Console.WriteLine("The result number is NEW NUMBER = {0} !", numberN);
            Console.ReadLine();
        }
    }
}