음료수 얼려먹기 - 파이썬

#음료수 얼려먹기
def DFS(graph,x,y):
  dx=[0,1,0,-1]
  dy=[1,0,-1,0]
  graph[x][y]=1
  for i in range(4):
    if(x+dx[i]>=0 and y+dy[i]>=0 and x+dx[i]<n and y+dy[i]<m):
      if graph[x+dx[i]][y+dy[i]]==0:
        graph[x+dx[i]][y+dy[i]]=1
        DFS(graph,x+dx[i],y+dy[i])


n,m=map(int,input().split())
graph = []
cnt=0
for i in range(n):
  graph.append(list(map(int, input())))
for i in range(n):
  for j in range(m):
    if(graph[i][j]==0):
      cnt+=1
      DFS(graph,i,j)
print(cnt)