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).