Visual C++ :: Map With Two Key Values?

I have an assignment where I need to go through all the files in a folder. For each file I need to know each unique file extension, how many files for each unique file extension, and the total size for each unique file extension. I have to be able to sort through this using either the file extension or the total size of the file extension. The first thing I thought of using was a map. This will keep track of each unique file extension and the amount of times that file extension was found. How do I now associate the total size of the file extension to my map? So for example I need the output to be something like this:

Using file extension for sort
.cpp : 1 : 3400
.exe : 3 : 3455600
.mp4 : 25 : 200000404

Using total file extension size for sort
.mp4 : 25 : 200000404
.exe : 3 : 3455600
.cpp : 1 : 3400

Here is the code I have so far:

Code:
#include <iostream>
#include <filesystem>
#include <map>

[Code]...

I was thinking of somehow using a class to implement this, but don't know how to go about doing that. A