# Given an m x n 2d grid map of '1's (land) and '0's (water), return the number of islands.

# An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.


# Example 1:

# Input: grid = [
# ["1","1","1","1","0"],
# ["1","1","0","1","0"],
# ["1","1","0","0","0"],
# ["0","0","0","0","0"]
# ]
# Output: 1
# Example 2:

# Input: grid = [
# ["1","1","0","0","0"],
# ["1","1","0","0","0"],
# ["0","0","1","0","0"],
# ["0","0","0","1","1"]
# ]
# Output: 3
