Programming Assignment #1: Operation Detector

Write a program that inputs three integers, and then reports if the last number is the sum, product, or difference of the first two.

Here are some example runs:

Enter three numbers:  5, 3, 15
15 is 3 * 5.

Enter three numbers:  4, 7, 10
10 is neither 4 + 7, 4 - 7, nor 4 * 7.

Enter three numbers:  0, 0, 0
0 is 0 + 0.
0 is 0 - 0.
0 is 0 * 0.