R

with open("input.txt", mode="r") as f_read:
    n, m = map(int, f_read.readline().strip().split())
    x_start, y_start = map(int, f_read.readline().strip().split())
    x_finish, y_finish = map(int, f_read.readline().strip().split())
    A = [list(i.strip()) for i in f_read.readlines()]

x_finish -= 1
y_finish -= 1

queue = [(x_start - 1, y_start - 1, "0")]

while len(queue) > 0:
    x, y, sub = queue.pop(0)
    A[x][y] = sub
    if (x, y) == (x_finish, y_finish):
        break
    if x > 0 and A[x - 1][y] == ".":
        queue.append((x - 1, y, str(int(sub)+1)))
    if x + 1 < n and A[x + 1][y] == ".":
        queue.append((x + 1, y, str(int(sub)+1)))
    if y > 0 and A[x][y - 1] == ".":
        queue.append((x, y - 1, str(int(sub)+1)))
    if y + 1 < m and A[x][y + 1] == ".":
        queue.append((x, y + 1, str(int(sub)+1)))

with open("output.txt", mode="w") as f_write:
    if A[x_finish][y_finish] == ".":
        print(-1)
    else:
        print(A[x_finish][y_finish])