4 5
00110
00011
11111
00000
# 3

15 14
00000111100000
11111101111110
11011101101110
11011101100000
11011111111111
11011111111100
11000000011111
01111111111111
00000000011111
01111111111000
00011111111000
00000001111000
11111111110011
11100011111111
11100011111111
# 8

n, m = map(int, input().split())
graph = [list(map(int, input())) for _ in range(n)]

def dfs(x, y):
    if x < 0 or y < 0 or x >= n or y >= m:
        return False
    if graph[x][y] == 0:
        graph[x][y] = 1
        dfs(x, y + 1)
        dfs(x + 1, y)
        dfs(x - 1, y)
        dfs(x, y - 1)
        return True
    return False

answer = 0
for i in range(n):
    for j in range(m):
        if dfs(i, j) == True:
            answer += 1
print(answer)

5 6
101010
111111
000001
111111
111111

n, m = map(int, input().split())
graph = [list(map(int, input())) for _ in range(n)]

dx = [-1, 0, 1, 0]
dy = [0, 1, 0, -1]

def bfs(x, y):
    queue = [(x, y)]
    while queue:
        x, y = queue.pop(0)
        for i in range(4):
            nx = x + dx[i]
            ny = y + dx[i]
            if nx < 0 or ny < 0 or nx >= n or ny >= m:
                continue
            if graph[nx][ny] == 0:
                continue
            elif graph[nx][ny] == 1:
                graph[nx][ny] = graph[x][y] + 1
                queue.append((x, y))
    return graph[n - 1][m - 1]

print(bfs(0, 0))