A “Caesar Cipher” is a simple way of encrypting a message by replacing each letter with a letter a certain number of spaces up the alphabet. For example, if shifting the message by 13 an A would become an N, while an S would wrap around to the start of the alphabet to become an F.

Write a program that asks the user for a message (a string) and a shift amount (an integer). The values should be passed to a function that accepts a string and an integer as arguments, and returns a string representing the original string encrypted by shifting the letters by the integer. For example, a string of “BEWARE THE IDES OF MARCH” and an integer of 13 should result in a string of “ORJNER GUR VQRF BS ZNEPU”.