Given a string as input, return a new string with each letter pushed to the right by its respective index in the alphabet.

We all know that A is a slow and Z is a fast letter. This means that Z gets shifted to the right by 25 spaces, A doesn't get shifted at all, and B gets shifted by 1 space.

You can assume the following things about your input:

It will only contain uppercase letters from A to Z, no whitespaces or punctuation;
Input strings will not exceed 100 characters (although your output string might!)
Note that if 2 or more letters fall onto the same space after shifting, the latest character will be used.