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

int main(){
    int H, W;
    cin >> H >> W;
    int sx, sy, gx, gy;
    cin >> sx >> sy >> gx >> gy;
    sx--; sy--; gx--; gy--;
    string S[1000];
    for(int i=0; i<H; i++) cin >> S[i];

    auto inside = [&](int i, int j){ return i>=0 && i<H && j>=0 && j<W && S[i][j] != '#'; };

    int dx[] = {0, 0, -1, 1};
    int dy[] = {-1, 1, 0, 0};

    queue<pair<int, int>> que;
    que.emplace(sx, sy);
    vector<vector<int>> dist(H, vector<int>(W, 1e9));
    dist[sx][sy] = 0;
    while(que.size()){
        auto p = que.front(); que.pop();
        int i = p.first, j = p.second;
        for(int k=0; k<4; k++){
            int x = i+dx[k], y = j+dy[k];
            if(inside(x, y) && dist[x][y] == 1e9){
                dist[x][y] = dist[i][j] + 1;
                que.emplace(x, y);
            }
        }
    }

    cout << dist[gx][gy] << endl;
    return 0;
}