BFS (152) 실패
from collections import deque
n, m = map(int, input().split())
graph = []
for _ in range(n):
graph.append(list(map(int, input())))
dx = [-1, 1, 0, 0]
dy = [0, 0, -1, 1]
def bfs(x, y):
queue = deque()
queue.append((x, y))
while queue:
x, y = queue.popleft()
for i in range(4):
nx = x + dx[i]
ny = y + dy[i]
if ( nx < 0 or ny < 0 or nx >= n or ny >= m ):
continue
if ( graph[nx][ny] == 0 ):
continue
if graph[nx][ny] == 1:
graph[nx][ny] = graph[x][y] + 1
queue.append((nx, ny))
return graph[n - 1][m - 1]
print(bfs(0, 0))