def bomberMan(n, grid):
    # Write your code here
    if n == 1:
        return grid
    
    if n % 2 == 0:
        return ['O'*c for i in range(r)]

    def detonate_bombs(grid):
        new_grid = [['O']*c for i in range(r)]
        
        for i in range(r):
            for j in range(c):
                if grid[i][j] == 'O':
                    new_grid[i][j] = '.'
                    for x, y in [(i-1, j), (i+1, j), (i, j-1), (i, j+1)]:
                        if 0<=x<r and 0<=y<c:
                            new_grid[x][y] = '.'
                            
        return [''.join(row) for row in new_grid]
    
    n //= 2
    for _ in range((n + 1) % 2 + 1):
        new_grid = detonate_bombs(grid)
        grid = new_grid
        
    return [''.join(row) for row in grid]