Problem Description

Given a 2D character matrix A of size N x M, containing 'X' and 'O', capture all regions surrounded by 'X'.

A region is captured by flipping all 'O's into 'X's in that surrounded region.

Problem Constraints

1 <= N, M <= 10³

Input Format

First and only argument 2D character matrix A of size N X M.

Output Format

Make changes to the the input only as matrix is passed by reference.

Example Input

Input 1:

 A = [  [X, X, X, X],
        [X, O, O, X],
        [X, X, O, X],
        [X, O, X, X]
     ]

Example Output

Output 1:

 A = [  [X, X, X, X],
        [X, X, X, X],
        [X, X, X, X],
        [X, O, X, X]
     ]

Example Explanation

Explanation 1:

 'O' in (4,2) is not surrounded by X from below.