Scary name, simple concept. The symmetric difference of two sets is the items of each set not present in the other set. Once again, however, the fact that a problem is simple has no bearing on how often we may or may not see it in real world situations.

This, in fact, was my last assignment at my previous position: I needed to report which records could be found in Database A that were not in Database B and vice versa. Those of you who have done the other challenges in this series may recognize a marked similarity to the very first challenge, but I'll be sure to add one wrinkle.

The challenge

Given two lists of values, determine which values are present in the first list but not in the second and vice versa. The output for this program will be the unique values from each list. As such, it is important to remember which list each item was on.

Your input data will be sorted.

Input data

[Here] ( are both your files. It's one gist, but there are two files. Be sure to scroll down.

These input files are sorted in ascending order.


As usual, the answer is base64-encoded. Good luck!