Consider a string, S, that is a series of characters, each followed by its frequency as an integer. The string is not compressed correctly, so there may be multiple occurrences of the same character. A properly compressed string will consist of one instance of each character in alphabetical order followed by the total count of that character within the string.
Example
The string ' a3c9b2c1' has two instances where ' c ' is followed by a count: once with 9  occurrences, and again with 1.  It should be compressed to ' a3b2c10' .
Function Description
Complete the function betterCompression in the editor below.

betterCompression has the following parameter:
S:  a compressed string

Returns:
string: the properly compressed string