#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef vector<vii> vvii;
#define fi first
#define se second
#define ALL(x) (x).begin(), (x).end()
#define RALL(x) (x).rbegin(), (x).rend()
#define eb emplace_back
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define SZ(x) (int)(x).size()
#define endl '\n'
#define FOR(a, b, c) for (auto a = (b); (a) < (c); ++(a))
#define F0R(a, b) FOR (a, 0, (b))
#define CEIL(a, b) ((a) + (b)-1) / (b)
template <class T>
bool ckmin(T& a, const T& b) {
  return a > b ? a = b, true : false;
}
template <class T>
bool ckmax(T& a, const T& b) {
  return a < b ? a = b, true : false;
}
#ifndef DEBUG
#define DEBUG 0
#endif
#define dout \
  if (DEBUG) std::cerr
#define dvar(...) " [" << #__VA_ARGS__ ": " << mt(__VA_ARGS__) << "] "
template <typename T>
struct IsC {
  template <typename C>
  static char test(typename C::const_iterator*);
  template <typename C>
  static int test(...);
  static const bool value = sizeof(test<T>(0)) == sizeof(char);
};
template <>
struct IsC<string> {
  static const bool value = false;
};
template <typename C>
typename enable_if<IsC<C>::value, ostream&>::type operator<<(ostream&, const C&);
template <typename T1, typename T2>
ostream& operator<<(ostream&, const pair<T1, T2>&);
template <typename... T> using TS = tuple_size<tuple<T...>>;
template<size_t idx, typename... T>
typename enable_if<TS<T...>::value == idx + 1, ostream&>::type
operator<<(ostream& o, const tuple<T...>& t) {
  return o << ", " << get<idx>(t) << ')';
}
template<size_t idx, typename... T>
typename enable_if<0 < idx && idx + 1 < TS<T...>::value, ostream&>::type
operator<<(ostream& o, const tuple<T...>& t) {
  return operator<<<idx + 1>(o << ", " << get<idx>(t), t);
}
template<size_t idx = 0, typename... T>
typename enable_if<1 < TS<T...>::value && !idx, ostream&>::type
operator<<(ostream& o, const tuple<T...>& t) {
  return operator<<<idx + 1>(o << '(' << get<idx>(t), t);
}
template<typename T>
ostream& operator<<(ostream& o, const tuple<T>& t) {
  return o << get<0>(t);
}
template <typename T1, typename T2>
ostream& operator<<(ostream& o, const pair<T1, T2>& p) {
  return o << mt(p.fi, p.se);
}
template <typename C>
typename enable_if<IsC<C>::value, ostream&>::type operator<<(
    ostream& o, const C& c) {
  o << '[';
  for (auto it = c.cbegin(); it != c.cend(); ++it)
    o << *it << (next(it) != c.cend() ? ", " : "");
  return o << ']';
}
template <typename T>
void tprint(vector<vector<T>>& v, size_t width = 0, ostream& o = cerr) {
  if (!DEBUG) return;
  for (const auto& vv : v) {
    for (const auto& i : vv) o << setw(width) << i;
    o << endl;
  }
}

array<int, 3> a;


void solve() {
    int h, w, fromR, fromC, toR, toC;
    cin >> h >> w >> fromR >> fromC >> toR >> toC;
    fromR--;
    fromC--;
    toR--;
    toC--;

    vector<vector<bool>> a(h, vector<bool>(w)),
        seen(h, vector<bool>(w)),
        walk(h, vector<bool>(w));

    F0R(r, h) F0R(c, w) {
        char ch;
        cin >> ch;
        a[r][c] = ch == '.';
    }

    set<array<int, 3>> q;
    array<int, 3> tmp;
    tmp[0] = 0;
    tmp[1] = fromR;
    tmp[2] = fromC;
    q.insert(tmp);
    while(SZ(q)) {

        array<int, 3> x = *q.begin();
        int cnt = x[0];
        int r = x[1];
        int c = x[2];
        q.erase(q.begin());
        seen[r][c] = true;

        if(r == toR && c == toC) {
            cout << cnt << endl;
            return;
        }

        FOR(dr, -2, 3) FOR(dc, -2, 3) {
            if(!dr && !dc) continue;
            int rr = r + dr;
            int cc = c + dc;

            if(min(rr, cc) < 0 || rr >= h || cc >= w || seen[rr][cc] || !a[rr][cc]) continue;

            array<int, 3> y;
            if((abs(dr) == 1 && !abs(dc)) || (abs(dc) == 1 && !abs(dr))) {
                y[0] = cnt;
            } else {
                y[0] = cnt + 1;
            }
            y[1] = rr;
            y[2] = cc;
            q.insert(y);
        }
    }

    cout << -1 << endl;

}

int main() {
    cin.tie(0);
    ios_base::sync_with_stdio(0);

    int tc = 1;
    FOR(i, 1, tc + 1) {
        //cout << "Case #" << i << ": ";
        solve();
    }
}



Measured memory_bytes: 4968