R, C = list(map(int, input().split(" ")))
sy, sx = list(map(int, input().split(" ")))
gy, gx = list(map(int, input().split(" ")))
field_list = []
position_list = []
for i in range(R):
    temp = input()
    temp_list = []
    for j in temp:
        temp_list.append(j)
    field_list.append(temp_list)
# print(field_list)


def BFF(x, y, count):
    if x == gx-1 and y == gy-1:
        print(count)
        exit()
    for mx, my in [[1, 0], [-1, 0], [0, 1], [0, -1]]:
        if 0 <= x+mx < C and 0 <= y+my < R:
            if (x+mx, y+my) not in position_list:
                if field_list[y+my][x+mx] == ".":
                    position_list.append((x+mx, y+my))
                    BFF(x+mx, y+my, count+1)


position_list.append((sx-1, sy-1))
BFF(sx-1, sy-1, 0)