2011/10/31 DamiáÏ M. GonzáÍez <gonzalezdamianm / hotmail.com>:
>  can't figure out how the program "counts" the M's, can't understand
> in what part size = size + a_number( guess it must be 1(?). I guess this
> is not easy to explain, by the way if you can give me a hand I'll take
> it! Thanks for your time.

First, understand that M and o are objects which have the string
values 'land' and 'water', respectively. The method actually counts
elements according to whether they equal 'land' or not; anything that
equals 'land' is also equal to M.