import sys from collections import deque # Read input R, C = map(int, sys.stdin.readline().split()) sy, sx = map(int, sys.stdin.readline().split()) gy, gx = map(int, sys.stdin.readline().split()) # Convert to 0-based indices sy -= 1 sx -= 1 gy -= 1 gx -= 1 # Read maze maze = [] for _ in range(R): row = sys.stdin.readline().strip() maze.append(row) # Initialize distance array and queue dist = [[-1] * C for _ in range(R)] q = deque() dist[sy][sx] = 0 q.append((sy, sx)) # Directions: up, down, left, right dx = [0, 0, -1, 1] dy = [-1, 1, 0, 0] # BFS loop while q: y, x = q.popleft() current_dist = dist[y][x] # Check if current position is the goal if y == gy and x == gx: print(current_dist) sys.exit() # Explore all four directions for i in range(4): ny = y + dy[i] nx = x + dx[i] # Check if the next cell is within bounds, not a wall, and not visited if 0 <= ny < R and 0 <= nx < C: if maze[ny][nx] == '.' and dist[ny][nx] == -1: dist[ny][nx] = current_dist + 1 q.append((ny, nx)) # According to the problem statement, the goal is always reachable, so this line is theoretically unreachable print(-1)