R, C = gets.split.map(&:to_i)
SY, SX = gets.split.map(&:to_i)
GY, GX = gets.split.map(&:to_i)
G = R.times.map { gets.chomp.chars }
DY = [-1, 0, 1, 0]
DX = [0, 1, 0, -1]

queue = []
queue << [SY - 1, SX - 1, 0]
visited = Array.new(R) { Array.new(C, false) }

until queue.empty?
  y, x, dist = queue.shift

  if y == GY - 1 && x == GX - 1
    puts dist
    exit
  end

  next if visited[y][x]
  visited[y][x] = true

  4.times do |i|
    ny = y + DY[i]
    nx = x + DX[i]
    next if G[ny][nx] == '#'

    queue << [ny, nx, dist + 1]
  end
end