Move *.py to folder
[erl] Polish ex1

Sum of first N numbers, 8 solutions
[erl] Problem 3

prime_factor(N) works, but slow — spends time for searching next prime
prime_factor1(N) works, but fast — uses simple increment
[erl] Problem 4

1. Converting int to list
2. Reverse list
Generating a set of productions and get max from them (have to find a
generic and lazy way).
[erl] Problem 5

An empty module.
[py] Problem 7

??
[py] Problem 8

Find a solution for sample.
Just splitting to check parts without 0.