5-11.py

from collections import deque


n,m = map(int,input().split())

graph = []

for i 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 nx>=n or ny<0 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))