#include<bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 1e9 + 7;
//const int mod = 998244353;

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;


template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 > &p) {
  os << p.first << " " << p.second;
  return os;
}

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second;
  return is;
}

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};

template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}

int W, H;
char mas[1000][1000];
int min_cost[1000][1000];

int GridBFS(int sx, int sy, char c) {
  const int vx[] = {0, 1, 0, -1}, vy[] = {1, 0, -1, 0};
  for(int i = 0; i < 1000; i++) {
    for(int j = 0; j < 1000; j++) min_cost[i][j] = inf;
  }

  using pii = pair< int, pair< int, int > >;
  priority_queue< pii, vector< pii >, greater< pii > > que;
  que.emplace(0, make_pair(sx, sy));
  min_cost[sx][sy] = 0;

  while(!que.empty()) {
    int cost;
    pair< int, int > p;
    tie(cost, p) = que.top();
    que.pop();
    if(mas[p.second][p.first] == c) return (min_cost[p.first][p.second]);
    for(int i = 0; i < 4; i++) {
      int nx = p.first + vx[i], ny = p.second + vy[i];
      if(nx < 0 || ny < 0 || nx >= W || ny >= H) continue;
      if(mas[ny][nx] == '#') continue;
      if(chmin(min_cost[nx][ny], min_cost[p.first][p.second])) {
        que.emplace(min_cost[nx][ny], make_pair(nx, ny));
      }
    }
    for(int i = -2; i <= 2; i++) {
      for(int j = -2; j <= 2; j++) {
        int nx = p.first + i, ny = p.second + j;
        if(nx < 0 || ny < 0 || nx >= W || ny >= H) continue;
        if(mas[ny][nx] == '#') continue;
        if(chmin(min_cost[nx][ny], min_cost[p.first][p.second] + 1)) {
          que.emplace(min_cost[nx][ny], make_pair(nx, ny));
        }
      }
    }
  }
  return (-1);
}

int main() {
  cin >> H >> W;
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  --a, --b, --c, --d;
  for(int i = 0; i < H; i++) {
    string s;
    cin >> s;
    for(int j = 0; j < W; j++) {
      mas[i][j] = s[j];
    }
  }
  mas[c][d] = 'G';
  cout << GridBFS(b, a, 'G') << "\n";
}



Measured memory_bytes: 8560