#include <iostream>
#include <vector>
#include <deque>

using namespace std;

const int INF = 10000000;

int h, w;
vector<vector<int>> field;
vector<pair<int, int>> steps;
vector<vector<vector<int>>> dist;
deque<pair<pair<int, int>, int>> q;

bool ok(int xh, int xw) {
    return 0 <= xh && xh < h && 0 <= xw && xw < w && field[xh][xw];
}

void bfs(int xh, int xw) {
    dist.assign(h, vector<vector<int>>(w, vector<int>(8, INF)));
    q.clear();
    for (int dir = 0; dir < 8; ++dir) {
        q.push_back({{xh, xw}, dir});
        dist[xh][xw][dir] = 1;
    }
    while (!q.empty()) {
        auto v = *q.begin();
        q.pop_front();
        int vh = v.first.first, vw = v.first.second, v_dir = v.second;
        for (int i = 0; i < 8; ++i) {
            int nh = vh + steps[i].first, nw = vw + steps[i].second;
            if (ok(nh, nw) && dist[nh][nw][i] > dist[vh][vw][v_dir] + (i != v_dir)) {
                dist[nh][nw][i] = dist[vh][vw][v_dir] + (i != v_dir);
                if (i == v_dir) {
                    q.push_front({{nh, nw}, i});
                } else {
                    q.push_back({{nh, nw}, i});
                }
            }
        }
    }
}

int main() {
    cin >> h >> w;
    field.assign(h, vector<int>(w, 0));
    for (int i = 0; i < h; ++i) {
        for (int j = 0; j < w; ++j) {
            char c;
            cin >> c;
            if (c == '.') {
                field[i][j] = 1;
            }
        }
    }
    int sh, sw, th, tw;
    cin >> sw >> sh >> tw >> th;
    --sw;
    sh = h - sh;
    --tw;
    th = h - th;
    for (int dh = -1; dh <= 1; ++dh) {
        for (int dw = -1; dw <= 1; ++dw) {
            if (dh != 0 || dw != 0) {
                steps.push_back({dh, dw});
            }
        }
    }
    int best = INF;
    bfs(sh, sw);
    for (int t_dir = 0; t_dir < 8; ++t_dir) {
        best = min(best, dist[th][tw][t_dir]);
    }
    if (best == INF) {
        cout << "-1\n";
    } else {
        cout << best << "\n";
    }
    return 0;
}