from collections import deque import sys def main(): # 读取输入 R, C = map(int, sys.stdin.readline().split()) sy, sx = map(int, sys.stdin.readline().split()) gy, gx = map(int, sys.stdin.readline().split()) grid = [sys.stdin.readline().strip() for _ in range(R)] # 转换为0-based索引 start = (sy - 1, sx - 1) goal = (gy - 1, gx - 1) # 初始化步骤数组和队列 steps = [[-1 for _ in range(C)] for _ in range(R)] q = deque() q.append(start) steps[start[0]][start[1]] = 0 # 四个方向 dirs = [(-1, 0), (1, 0), (0, -1), (0, 1)] while q: i, j = q.popleft() if i == goal[0] and j == goal[1]: print(steps[i][j]) return for di, dj in dirs: ni = i + di nj = j + dj if 0 <= ni < R and 0 <= nj < C: if grid[ni][nj] == '.' and steps[ni][nj] == -1: steps[ni][nj] = steps[i][j] + 1 q.append((ni, nj)) # 根据题目描述,一定可以到达,所以无需处理无法到达的情况 print(-1) if __name__ == "__main__": main()