#include <bits/stdc++.h>
using namespace std;
using PP = pair<int, int>;
using TT = pair<int, PP>;
int h, w;
int si, sj;
int gi, gj;
char s[1004][1004];
int main() {
  cin >> h >> w >> si >> sj >> gi >> gj;
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      cin >> s[i + 1][j + 1];
    }
  }
  h += 2;
  w += 2;
  
  const int di[] = { 0, 1, 0, -1 };
  const int dj[] = { 1, 0, -1, 0 };
  queue<TT> que;
  que.push(TT(0, PP(si, sj)));
  while (!que.empty()) {
    TT t = que.front(); que.pop();
    int d = t.first;
    int i = t.second.first;
    int j = t.second.second;
    if (i < 0 || i >= h) continue;
    if (j < 0 || j >= w) continue;
    if (s[i][j] == '#') continue;
    if (i == gi && j == gj) {
      cout << d << endl;
      return 0;
    }
    for (int k = 0; k < 4; ++k) {
      que.push(TT(d + 1, PP(i + di[k], j + dj[k])));
    }
  }
}