# キュークラスの作成
class queue:
    def __init__(self, *item):
        self.queue = [i for i in item]
        self.top = len(self.queue)
    
    def enqueue(self, *item):
        self.queue += [i for i in item]
    
    def dequeue(self):
        try:
            _, *self.queue = self.queue
            return _
        except:
            return [None, None, None]

N, M = map(int, input().split())
s, s1 = map(int, input().split())
g, g2 = map(int, input().split())
maze = [','.join(input()).split(',') for i in range(M)]

maze[s1 - 1][s - 1] = 'S'
maze[g2 - 1][g - 1] = 'G'

# 次進む方向一覧
d = [[0, 1], [1, 0], [-1, 0], [0, -1]]

lists = queue([s - 1, s1 - 1, 0])
 
gone = [[False for i in range(N)] for j in range(M)] 

# ここから幅優先探索
for i in range(10000000):
    *now, times = lists.dequeue()

    for i in d:
        next_to = [i + j for i, j in zip(now, i)]
        
        # はみ出るかどうか
        if next_to[0] < 0 or next_to[0] >= M or next_to[1] < 0 or next_to[1] >= N:
            continue
            
        # すでにいったことがあるかどうか
        if gone[next_to[0]][next_to[1]]:
            continue
        
        # ゴールかどうか
        if maze[next_to[0]][next_to[1]] == 'G':
            print(times + 1)
            loop = False
            break
            
        # 道かどうか
        if maze[next_to[0]][next_to[1]] == '.':
            gone[next_to[0]][next_to[1]] = True
            lists.enqueue(next_to + [times + 1])