You must find the Levenshtein distance between two strings.
The Levenstein distance is the minimum number of single-character edits (insertions, deletions or substitutions) required to change one string into the other.
Ex: "kitten" and "sitting". The distance is 3.
kitten -> kittin -> sittin -> sitting
NB: This distance has a wide range of applications, for instance, spell checkers, correction systems for optical character recognition and many other.
