TakeDigitsFromNumber

using System;

//Write a program that takes as input a four-digit number in format abcd (e.g. 2011) and performs the following:
//•   Calculates the sum of the digits (in our example 2+0+1+1 = 4).
//•   Prints on the console the number in reversed order: dcba (in our example 1102).
//•   Puts the last digit in the first position: dabc (in our example 1201).
//•   Exchanges the second and the third digits: acbd (in our example 2101).
//The number has always exactly 4 digits and cannot start with 0


class FourDigitNumber
{
    static void Main()
    {
        Console.Write("Enter a four-digit number: ");
        int n = Math.Abs(int.Parse(Console.ReadLine()));
        int lastDigit = n % 10;
        int thirdDigit = (n / 10) % 10;
        int secondDigit = (n / 100) % 10;
        int firstDigit = (n / 1000) % 10;
        int sumOfDigits = firstDigit + secondDigit + thirdDigit +lastDigit;
        Console.WriteLine("The sum of the digits is: {0}", sumOfDigits);
        Console.WriteLine("The number in reversed order is: {0}{1}{2}{3}", lastDigit, thirdDigit, secondDigit, firstDigit);
        Console.WriteLine("When the last digit comes first, the number is: {0}{1}{2}{3}", lastDigit, firstDigit,secondDigit, thirdDigit);
        Console.WriteLine("When the second an the third digits are exchanged, the number is: {0}{1}{2}{3}", firstDigit, thirdDigit, secondDigit, lastDigit);


    }
}