#include <bits/stdc++.h>
using namespace std;
#define X ios_base::sync_with_stdio(false); cin.tie(NULL);
#define FIXED_FLOAT(x) std::fixed <<std::setprecision(2)<<(x)


void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif


// long long p = 1e9+7;

typedef long long ll;
typedef pair<ll,ll> pl;
typedef vector<int> VI;
typedef vector<pair<ll,ll>> VP;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef vector<bool> VB;

// typedef pair<ll, ll> PL;
typedef unordered_map<ll, ll> UMP;
#define FOR(i,b,init) for(i=init;i<b;i++)
#define pb push_back
#define fi first
#define se second
#define mp make_pair

// typedef  unordered_set<ll>;


// void printa(VI &x,ll n){
//     ll i;
//     FOR(i, n){
//         cout<<x[i]<<" ";
//     }
//     cout<<endl;
// }



/////GLOABLS VARS
ll MOD = 1e9+7;
ll gmx = 1e6+7;

VL fact(gmx, 1);
//////FUNCTIONS
ll powp(ll val, ll deg)
{
    // debug(val, deg);
    if (!deg)
        return 1;
    if (deg & 1)
        return (powp(val, deg - 1) * val) % MOD;
    ll res = powp(val, deg >> 1);
    // debug(res);
    return (res * res) % MOD;
}
ll mx=1e5+7;
vector<VL> adj;
VL sub;
ll n;

void dfs(ll r, ll parent){
    sub[r]=1;
    // debug(r,parent);
    for(auto k: adj[r]){
        if(k==parent){continue;}
        dfs(k, r);
        sub[r]+=sub[k];
    }
    return;
}

//It is not easy but it can be fun, if you think!!!

//
// ll mx = 2*1e5+7;
// vector<vector<pl>> adj;


int main(){
      ios::sync_with_stdio(0);
      cin.tie(0);
    // #ifndef ONLINE_JUDGE
    //     freopen("input.txt", "r", stdin);
    //     freopen("output.txt", "w", stdout);
    //     #define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
    // #endif
    ll n,i,j,m;
    cin>>n>>m;
    pl st,end;
    cin>>st.fi>>st.se>>end.fi>>end.se;
    st.fi--;st.se--;end.fi--;end.se--;
    vector<string>l(n);
    FOR(i,n,0){
        cin>>l[i];
    }
    queue<pl> q, waitq;
    q.push(st);
    vector<VL> vis(n, vector<ll>(m,1e18));
    vis[st.fi][st.se]=0;
    VL dir{1,0,-1};
    // VL magic
    bool flag=false;
    ll mag=0;
    while((q.size()>0) || (waitq.size()>0)){
        if(q.size()==0){
            while(waitq.size()>0){
                pl el=waitq.front(); waitq.pop();
                if(vis[el.fi][el.se]>mag){
                    // vis[el.fi][el.se]=vis[el.fi][el.se]-1e18;
                    q.push(el);
                    // mag++;

                }
            }
            continue;
        }
        pl el=q.front();
        q.pop();
        mag = max(mag, vis[el.fi][el.se]);
        if(el==end){
            break;
        }
        for(auto x:dir){
            for(auto y:dir){
                if(abs(x)==abs(y)){
                    continue;
                }
                ll nbx = x+el.fi, nby = y+el.se;
                if((nbx>=n) || (nbx<0) || (nby>=m) || (nby<0)){
                    continue;
                }
                if((vis[nbx][nby]>vis[el.fi][el.se]) && l[nbx][nby]=='.'){
                    vis[nbx][nby] = vis[el.fi][el.se];
                    q.push(mp(nbx,nby));
                }
            }
        }
        for(i=max((ll)0, el.fi-2); i<min(n, el.fi+3);i++){
            for(j=max((ll)0, el.se-2); j<min(m, el.se+3);j++){
                if((vis[i][j]>vis[el.fi][el.se]+1) && (l[i][j]=='.')){
                    vis[i][j] = 1+vis[el.fi][el.se];
                    waitq.push(mp(i,j));
                }
            }
        }

    }
    // debug(vis);
    if(vis[end.fi][end.se]==1e18){
        cout<<-1;
    }
    else{
        cout<<vis[end.fi][end.se];
    }
    // cout.flush();




}