#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i,n)for (int i = 0; i < int(n); ++i)
#define rrep(i,n)for (int i = int(n)-1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
template<class T> void chmax(T& a, const T& b) {a = max(a, b);}
template<class T> void chmin(T& a, const T& b) {a = min(a, b);}
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
constexpr int INF = 1001001001;
int dist[1000][1000][6];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    rep(i, 1000) rep(j, 1000) rep(k, 6) dist[i][j][k] = INF;
    int h, w;
    cin >> h >> w;
    int sx, sy;
    cin >> sx >> sy;
    sx--, sy--;
    int gx, gy;
    cin >> gx >> gy;
    gx--, gy--;
    vector<string> s(h);
    rep(i, h) cin >> s[i];
    queue<tuple<int, int, int>> q;
    auto push = [&](int i, int j, int k, int d) {
        if (dist[i][j][k] == INF) {
            dist[i][j][k] = d;
            q.emplace(i, j, k);
        }
    };
    push(sx, sy, 4, 0);
    while(!q.empty()) {
        auto [i, j, k] = q.front(); q.pop();
        int nd = dist[i][j][k] + 1;
        rep(direction, 4) {
            int ni = i + dx[direction], nj = j + dy[direction];
            if (!(0 <= ni && ni < h && 0 <= nj && nj < w && s[ni][nj] == '.')) {
                continue;
            }
            int nk = (
                k == 4 ? direction :
                k == 5 ? direction ^ 2 :
                ((direction ^ k) & 1) ? k :
                direction == k ? 5 : 4
            );
            push(ni, nj, nk, nd);
        }
    }
    int ans = dist[gx][gy][4];
    if (ans == INF) ans = -1;
    cout << ans << '\n';
}