import itertools

if __name__ == '__main__':
    h, w = map(int, input().split())
    matrix = [list(map(int, input().split())) for _ in range(h)]
    
    diffs = ((1, 0), (-1, 0), (0, 1), (0, -1))
    counter = 2
    for x, y in itertools.product(range(h), range(w)):
        if matrix[x][y] == 0: continue

        ponds = [(x, y)]
        for dx, dy in diffs:
            i, j = x + dx, y + dy
            if 0 <= i < h and 0 <= j < w and matrix[i][j] != 0: ponds.append((i, j))
        
        coordinate = min((matrix[i][j] for i, j in ponds if matrix[i][j] != 1), default=counter)
        if coordinate == counter: counter += 1

        for i, j in ponds: matrix[i][j] = coordinate
    
    answer = max(map(max, matrix))
    if answer != 0: answer -= 1
    print(answer)