#include <bits/stdc++.h>
using namespace std;

int R, C, sy, sx, gy, gx;
vector<vector<char>> c;
vector<vector<int>> ans;

void bfs() {
  queue<pair<int, int>> q;
  q.push(make_pair(sy, sx));
  ans[sy][sx] = 0;

  while (!q.empty()) {
    int y = q.front().first, x = q.front().second;
    q.pop();

    int dy[] = {1, 0, -1, 0}, dx[] = {0, 1, 0, -1};
    for (int i = 0; i < 4; ++i) {
      int ny = y + dy[i], nx = x + dx[i];
      if (ny < 0 || R <= ny || nx < 0 || C <= nx) {
        continue;
      }
      if (ans[ny][nx] != -1) {
        continue;
      }
      q.push(make_pair(ny, nx));
      ans[ny][nx] = ans[y][x] + 1;
    }
  }
}

int main() {
  cin >> R >> C >> sy >> sx >> gy >> gx;
  c.resize(R, vector<char>(C)), ans.resize(R, vector<int>(C, -1));
  for (int i = 0; i < R; ++i) {
    for (int j = 0; j < C; ++j) {
      cin >> c[i][j];
    }
  }
  --sy, --sx, --gy, --gx;
  bfs();
  cout << ans[gy][gx] << endl;
}