//author: JainBot27
//Created on: 08/22/20
#pragma GCC optimize("Ofast")
#pragma GCC target("sse4,avx,avx2,fma")
#include <bits/stdc++.h>
using namespace std;


#define f first
#define s second
#define pb push_back
#define mp make_pair
#define ts to_string
#define ub upper_bound
#define lb lower_bound
#define ar array
#define all(x) x.begin(), x.end()
#define siz(x) (int)x.size()
#define FOR(x, y, z) for(int x = (y); x < (z); x++)
#define ROF(x, y, z) for(int x = (y-1); x >= (z); x--)
#define F0R(x, z) FOR(x, 0, z)
#define R0F(x, z) ROF(x, z, 0)
#define trav(x, y) for(auto&x:y)


const string nl = "\n";
using ll = int64_t;
using vi = vector<int>;
using vl = vector<ll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using str = string;
using vpii = vector<pii>;
using vpll = vector<pll>;


template<class T> inline bool ckmin(T&a, T b) {return b < a ? a = b, 1 : 0;}
template<class T> inline bool ckmax(T&a, T b) {return b > a ? a = b, 1 : 0;}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());


str ts(char c) { return str(1,c); }
str ts(bool b) { return b ? "true" : "false"; }
str ts(const char* s) { return (str)s; }
str ts(str s) { return s; }
template<class A> str ts(complex<A> c) { 
    stringstream ss; ss << c; return ss.str(); }
str ts(vector<bool> v) { 
    str res = "{"; for(int i = 0;i < (int)v.size(); i++) res += char('0'+v[i]);
    res += "}"; return res; }
template<size_t SZ> str ts(bitset<SZ> b) {
    str res = ""; for(int i = 0; i < b.size(); i++) res += char('0'+b[i]);
    return res; }
template<class A, class B> str ts(pair<A,B> p);
template<class T> str ts(T v) { 
    bool fst = 1; str res = "{";
    for (const auto& x: v) {
        if (!fst) res += ", ";
        fst = 0; res += ts(x);
    }
    res += "}"; return res;
}
template<class A, class B> str ts(pair<A,B> p) {
    return "("+ts(p.f)+", "+ts(p.s)+")"; }
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) {
    cerr << ts(h); if (sizeof...(t)) cerr << ", ";
    DBG(t...); }


#ifdef D 
#define dbg(...) cerr << "LINE(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif
const int mxN = 1e3;
int dx[] = {0, 0, -1, 1};
int dy[] = {-1, 1, 0, 0};
char g[mxN][mxN]; int d[mxN][mxN], w[4], n, m;
priority_queue<ar<int, 3>, vector<ar<int, 3>>, greater<ar<int, 3>>> pq;

bool good(int a, int b){
    return a >= 0 && b >= 0 && a < n && b < m && g[a][b] != '#';
}
signed main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> n >> m;
    F0R(i,4) cin >> w[i], w[i]--;
    F0R(i, n){
        F0R(j, m){
            cin >> g[i][j];
        }
    }
    memset(d, 0x3f, sizeof(d));
    d[w[0]][w[1]] = 0;
    pq.push({0, w[0], w[1]});
    while(!pq.empty()){
        ar<int, 3> x = pq.top(); pq.pop();
        dbg(x);
        if(d[x[1]][x[2]] > x[0])
            continue;
        for(int i=0; i < 4; i++){
            int xx = x[1] + dx[i]; int yy = x[2] + dy[i];
            if(good(xx, yy)){
                if(d[xx][yy] > x[0]){
                    d[xx][yy] = x[0];
                    pq.push({d[xx][yy], xx, yy});
                }
            }
        }
        for(int i=-2; i <= 2; i++){
            for(int j=-2; j <= 2; j++){
                int xx = x[1] + i; int yy = x[2] + j;
                if(good(xx, yy)){
                    if(d[xx][yy] > x[0] + 1){
                        d[xx][yy] = x[0] + 1;
                        pq.push({d[xx][yy], xx, yy});
                    }
                }
            }
        }
    }
    if(d[w[2]][w[3]] >= (int)1e9){
        cout << -1 << nl;
    }
    else{
        cout << d[w[2]][w[3]] << nl;
    }
}
/*
 * Stuff I should try:
 * Is it Monotonic? -> Binary Search
 * Is N small? -> Bitsets or other exponential
 * Edge Cases? Look Carefully 
 * Can't figure anything out? Brute Force and see patterns
 * Try to prove greedies
 * Prefix Sums, Amortization, DP, Data Structures
*/


Measured memory_bytes: 8504