Count the Islands

A map is a list of strings of equal length, where '#' is land and '.' is water. Land squares that touch up, down, left or right belong to the same island; squares that meet only at a corner do not. Write count_islands(grid) that returns how many islands the map has.

Examples

grid = [
    '##..#',
    '##...',
    '..#..',
    '...##',
]
count_islands(grid)  # returns 4
count_islands(['#.', '.#'])  # returns 2
count_islands(['...'])  # returns 0

The first map has four islands: the 2 by 2 block, the single square at the top right, the square in the middle and the pair at the bottom right. In the second map the two squares meet only at a corner, so they are separate islands.

Constraints

• 0 to 50 rows, each with 1 to 50 characters.
• Every character is '#' or '.'.