import sys
sys.setrecursionlimit(10**6)
h,w=map(int,input().split())
grid=[list(map(int,input().split())) for i in range(h)]
f=[[0]*w for i in range(h)]
cnt = 1
l=[1,0,-1,0]
r=[0,1,0,-1]

def dfs(x,y):
    f[x][y] = cnt
    for i in range(4):
        if 0 <= x + l[i] < h and 0 <= y + r[i] < w:
            if grid[x+l[i]][y+r[i]] == 1 and f[x+l[i]][y+r[i]] == 0:
                dfs(x+l[i],y+r[i])


for i in range(h):
    for j in range(w):
        if grid[i][j] == 1 and f[i][j] ==0:
            dfs(i,j)
            cnt += 1
            
print(cnt-1)