#include <bits/stdc++.h>

using namespace std;

const int INF = 1000000000;
char c[50][50];
int H, W, sy, sx, gy, gx, d[50][50], dy[4] = {1, 0, -1, 0}, dx[4] = {0, 1, 0, -1};

int bfs() {
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++)
      d[i][j] = INF;
  }
  queue<pair<int, int> > q;
  q.push(make_pair(sy, sx));
  d[sy][sx] = 0;
  while (q.size()) {
    pair<int, int> p = q.front();
    q.pop();
    for (int i = 0; i < 4; i++) {
      int ny = p.first + dy[i], nx = p.second + dx[i];
      if (0 <= ny && ny < H && 0 <= nx && nx < W && c[ny][nx] != '#' && d[ny][nx] == INF) {
        q.push(make_pair(ny, nx));
        d[ny][nx] = d[p.first][p.second] + 1;
      }
    }
  }
  return d[gy][gx];
}

void solve() {
  int x = bfs();
  printf("%d\n", x);
  return;
}

int main() {
  cin >> H >> W >> sy >> sx >> gy >> gx;
  sy -= 1; sx -= 1; gy -= 1; gx -= 1;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> c[i][j];
    }
  }
  solve();
  return 0;
}