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

int main() {
    int h, w;
    cin >> h >> w;
    vector<vector<int>> g(h+2, vector<int>(w+2, 1));
    vector<vector<int>> ans(h+2, vector<int>(w+2, 1001001001));
    vector<vector<int>> seen(h+2, vector<int>(w+2, 0));
    pair<int, int> start, goal;
    cin >> start.first >> start.second;
    cin >> goal.first >> goal.second;
    for(int i=1;i<=h;i++) for(int j=1;j<=w;j++) {
        char c;
        cin >> c;
        if(c == '.') g[i][j] = 0;
    }
    if(g[start.first][start.second]){
      cout << 0 << endl;
      return 0;
    }
    if(g[goal.first][goal.second]) {
      cout << 0 << endl;
      return 0;
    }
    queue<pair<int, int>> que;
    que.emplace(start);
    ans[start.first][start.second] = 0;
    while(!que.empty()) {
        pair<int, int> p = que.front();que.pop();
        if(seen[p.first][p.second]) continue;
        seen[p.first][p.second] = 1;
        int now = ans[p.first][p.second];
        if(!g[p.first][p.second+1] && ans[p.first][p.second+1] > now + 1) {
            ans[p.first][p.second+1] = now + 1;
            que.emplace(make_pair(p.first, p.second+1));
        }
        if(!g[p.first][p.second-1] && ans[p.first][p.second-1] > now + 1) {
            ans[p.first][p.second-1] = now + 1;
            que.emplace(make_pair(p.first, p.second-1));
        }
        if(!g[p.first-1][p.second] && ans[p.first-1][p.second] > now + 1) {
            ans[p.first-1][p.second] = now + 1;
            que.emplace(make_pair(p.first-1, p.second));
        }
        if(!g[p.first+1][p.second] && ans[p.first+1][p.second] > now + 1) {
            ans[p.first+1][p.second] = now + 1;
            que.emplace(make_pair(p.first+1, p.second));
        }
    }
    if(ans[goal.first][goal.second] == 1001001001) cout << 0 << endl;
    else cout << ans[goal.first][goal.second] << endl;
    return 0;
}