R,C = map(int,input().split())
sy,sx = map(int,input().split())
gy,gx= map(int,input().split())
C = [input()for _ in range(C)]
sy -= 1;sx -= 1;gy -= 1;gx -= 1
dist = [[2**60]*R for _ in range(C)]
dist[sy][sx] = 0
from collections import deque
que = deque([(sy,sx)])
d = [-1,1]
visited = [[0]*R for _ in range(C)]
visited[sy][sx] = 1
while que:
    u = que.popleft()
    y,x = u
    for i in range(2):
        yy = y+d[i]
        xx = x+d[i]
        if 0 <= yy < C:
            dist[yy][x] = min(dist[yy][x],dist[y][x]+1)
            if visited[yy][x] == 0:
                que.append((yy,x))
                visited[yy][x] = 1
        if 0 <= xx < R:
            dist[y][xx] = min(dist[y][xx],dist[y][x]+1)
            if visited[y][xx] == 0:
                que.append((y,xx))
                visited[y][xx] = 1     
print(dist[gy][gx])