1
import sys
2
input = sys.stdin.read
3

4
def main():
5
    data = input().split()
6
    n, m = int(data[0]), int(data[1])
7
    index = 2
8
    graph = [[0] * m for _ in range(n)]
9
    for i in range(n):
10
        for j in range(m):
11
            graph[i][j] = int(data[index])
12
            index += 1
13
    visited = [[False] * m for _ in range(n)]
14

15
    def dfs(x, y):
16
        if x < 0 or x >= n or y < 0 or y >= m:
17
            return
18
        if graph[x][y] == 0 or visited[x][y]:
19
            return
20
        visited[x][y] = True
21
        dfs(x - 1, y)
22
        dfs(x + 1, y)
23
        dfs(x, y - 1)
24
        dfs(x, y + 1)
25

26
    res = 0
27
    for i in range(n):
28
        for j in range(m):
29
            if graph[i][j] == 1 and not visited[i][j]:
30
                dfs(i, j)
31
                res += 1
32

33
    print(res)
34

35
main()

1
import sys
2
from collections import deque
3
input = sys.stdin.read
4

5
def main():
6
    data = input().split()
7
    n, m = int(data[0]), int(data[1])
8
    index = 2
9
    graph = [[0] * m for _ in range(n)]
10
    for i in range(n):
11
        for j in range(m):
12
            graph[i][j] = int(data[index])
13
            index += 1
14

15
    visited = [[False] * m for _ in range(n)]
16

17
    def bfs(x, y):
18
        queue = deque()
19
        queue.append((x, y))
20
        visited[x][y] = True
21

22
        while queue:
23
            cx, cy = queue.popleft()
24
            for nx, ny in [(cx - 1, cy), (cx + 1, cy), (cx, cy - 1), (cx, cy + 1)]:
25
                if 0 <= nx < n and 0 <= ny < m:
26
                    if graph[nx][ny] == 1 and not visited[nx][ny]:
27
                        visited[nx][ny] = True
28
                        queue.append((nx, ny))
29

30
    res = 0
31
    for i in range(n):
32
        for j in range(m):
33
            if graph[i][j] == 1 and not visited[i][j]:
34
                bfs(i, j)
35
                res += 1
36

37
    print(res)
38

39
main()

1
import sys
2
input = sys.stdin.read
3

4
def main():
5
    data = input().split()
6
    n, m = int(data[0]), int(data[1])
7
    index = 2
8
    graph = [[0] * m for _ in range(n)]
9
    for i in range(n):
10
        for j in range(m):
11
            graph[i][j] = int(data[index])
12
            index += 1
13
    visited = [[False] * m for _ in range(n)]
14

15
    def dfs(x, y):
16
        if x < 0 or x >= n or y < 0 or y >= m:
17
            return 0
18
        if graph[x][y] == 0 or visited[x][y]:
19
            return 0
20
        visited[x][y] = True
21
        area = 1
22
        area += dfs(x - 1, y)
23
        area += dfs(x + 1, y)
24
        area += dfs(x, y - 1)
25
        area += dfs(x, y + 1)
26
        return area
27

28
    res = 0
29
    for i in range(n):
30
        for j in range(m):
31
            if graph[i][j] == 1 and not visited[i][j]:
32
                res = max(res, dfs(i, j))
33

34
    print(res)
35

36
main()