UVa 10591 - Happy Number

Problem Number - Problem Name

 * [Problem Link]

Summary
Summary of the problem statement goes here.

Explanation
Explanation of the ideas behind the solution goes here.

Gotchas

 * Any points one can easily overlook?
 * The correct way to understand ambiguous formulations?

Optimizations
Optimizations here.

Input
3 7 4 13

Output
Case #1: 7 is a Happy number. Case #2: 4 is an Unhappy number. Case #3: 13 is a Happy number.