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

typedef long long ll;
#define pa pair<int, int>
#define pal pair<long long, long long>
#define pali pair<long long, int>
#define pad pair<double, double>
#define pb push_back
#define mp make_pair
#define COUT(v)                              \
    for (int64_t i = 0; i < (v).size(); ++i) \
    {                                        \
        cout << v.at(i) << endl;             \
    }
#define REP(i, n) for (int64_t i = 0; i < n; ++i)
#define FOR(i, r, n) for (int64_t i = (r); i < n; ++i)
#define VIN(v)                               \
    for (int64_t i = 0; i < (v).size(); ++i) \
    {                                        \
        cin >> (v).at(i);                    \
    }

typedef vector<bool> bvec;
typedef vector<int> ivec;
typedef vector<long long> lvec;
typedef vector<double> dvec;
typedef vector<pa> pavec;
typedef vector<vector<pa>> pamat;
typedef vector<pali> palivec;
typedef vector<pal> palvec;

typedef vector<vector<bool>> bmat;
typedef vector<vector<int>> imat;
typedef vector<vector<long long>> lmat;

typedef vector<string> svec;
typedef vector<vector<string>> smat;
const ll infll = (1LL << 60) - 1;
const int inf = (1 << 30) - 1;
const ll MOD = 1000000007;

ll gcd(ll x, ll y)
{
    ll r = x % y;
    if (r == 0)
        return y;
    else
        return gcd(y, r);
}

ll lcm(ll x, ll y)
{
    return x * y / gcd(x, y);
}

lvec mfactor(ll n)
{
    bvec ip(n, true);
    lvec mf(n, -1);
    ip[0] = false;
    ip[1] = false;
    mf[0] = 0;
    mf[1] = 1;
    REP(i, n)
    {
        if (ip[i])
        {
            mf[i] = i;
            for (ll j = i * i; j < n; j += i)
            {
                ip[j] = false;
                if (mf[j] == -1)
                    mf[j] = i;
            }
        }
    }
    return mf;
}

palivec get_prime(ll n, const lvec &mf)
{
    palivec plist;
    while (n != 1)
    {
        int cnt = 0;
        ll m = mf[n];
        while (mf[n] == m)
        {
            cnt++;
            n /= m;
        }
        plist.pb(pali(m, cnt));
    }
    return plist;
}

void COMinit(int m, lvec &fac, lvec &finv)
{
    lvec inv(m);
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < m; i++)
    {
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

ll pow_mod(ll a, ll n)
{
    ll x = 1;
    while (n > 0)
    {
        if (n & 1)
        {
            x = x * a % MOD;
        }
        a = a * a % MOD;
        n >>= 1;
    }
    return x;
}

ll COM(int n, int k, const lvec &fac, const lvec &finv)
{
    if (n < k)
        return 0;
    if (n < 0 || k < 0)
        return 0;
    return (fac[n] * (finv[k] * finv[n - k] % MOD)) % MOD;
}

ll modinv(ll a, ll m)
{
    ll b = m, u = 1, v = 0;
    while (b)
    {
        ll t = a / b;
        a -= t * b;
        swap(a, b);
        u -= t * v;
        swap(u, v);
    }
    u %= m;
    if (u < 0)
        u += m;
    return u;
}

ll cnt(ll x)
{
    ll s = 0;
    ll k = 26;
    for (int i = 0; i < x; i++)
    {
        s = s + k;
        k *= 26;
    }
    return s;
}

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll h, w, ch, cw, dh, dw;
    cin >> h >> w >> ch >> cw >> dh >> dw;
    --ch, --cw, --dh, --dw;
    svec s(h);
    for (int i = 0; i < h; i++)
    {
        for (int j = 0; j < w; j++)
        {
            char c;
            cin >> c;
            s[i].pb(c);
        }
    }
    priority_queue<pair<ll, pal>, vector<pair<ll, pal>>, greater<pair<ll, pal>>> q;
    q.push(pair<ll, pal>(0, pal(ch, cw)));
    lmat dp(h, lvec(w, -1));

    while (!q.empty())
    {

        auto qq = q.top();
        q.pop();
        ll v = qq.first;
        pal p = qq.second;
        ll hh = p.first, ww = p.second;
        if (dp[hh][ww] != -1)
            continue;
        dp[hh][ww] = v;

        if (hh == dh && ww == dw)
        {
            cout << v << endl;
            return 0;
        }

        if (ww - 1 >= 0)
        {
            if (s[hh][ww - 1] == '.' && dp[hh][ww - 1] == -1)
            {
                q.push(pair<ll, pal>(v, pal(hh, ww - 1)));
            }
        }

        if (ww + 1 < w)
        {

            if (s[hh][ww + 1] == '.' && dp[hh][ww + 1] == -1)
            {
                q.push(pair<ll, pal>(v, pal(hh, ww + 1)));
            }
        }

        if (hh - 1 >= 0)
        {
            if (s[hh - 1][ww] == '.' && dp[hh - 1][ww] == -1)
            {
                q.push(pair<ll, pal>(v, pal(hh - 1, ww)));
            }
        }

        if (hh + 1 < h)
        {
            if (s[hh + 1][ww] == '.' && dp[hh + 1][ww] == -1)
            {
                q.push(pair<ll, pal>(v, pal(hh + 1, ww)));
            }
        }

        for (int i = -2; i < 3; i++)
        {
            for (int j = -2; j < 3; j++)
            {
                if (hh + i < 0 || hh + i > h - 1 || ww + j < 0 || ww + j > w - 1 || ((i == 0) && (j == 0)))
                {
                    continue;
                }

                if (s[hh + i][ww + j] == '.' && dp[hh + i][ww + j] == -1)
                {
                    q.push(pair<ll, pal>(v + 1, pal(hh + i, ww + j)));
                }
            }
        }
    }

    cout << dp[dh][dw] << endl;
}


Measured memory_bytes: 16036