#include<bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long int
using namespace __gnu_pbds;
typedef tree<pair<ll,pair<ll,ll> >, null_type, less<pair<ll,pair<ll,ll> > >, rb_tree_tag, tree_order_statistics_node_update>ordered_set;
#define me BOSS
#define bug() cout<<"AIkahne aise"<<endl
#define PI acos(-1)
/* Precode Start Here *\
     Sieve
void sieve()
{
    for(ll i=3; i<=2000; i+=2)
    {
        for(ll j=i*i; j<=4000000; j+=i)
            A[j]=1;
    }
    v.push_back(2);
    for(ll i=3; i<=4000000; i+=2)
        if(A[i]==0)
            v.push_back(i);
}

     Power Function Modulo P

ll modPow(ll a, ll x, ll p) {
    //calculates a^x mod p in logarithmic time.
    long res = 1;
    while(x > 0) {
        if( x % 2 != 0) {
            res = (res * a) % p;
        }
        a = (a * a) % p;
        x /= 2;
    }
    return res;
}


   factorial

ll fact(ll n)
{
    ll ans=1;
    for(ll i=1;i<=n;i++)
    {
        ans=(ans*i)%mod;
    }
    return ans;
}
     Calculating nCr using Fermats law Theorem

ll modInverse(ll a, ll p) {
    //calculates the modular multiplicative of a mod m.
    //(assuming p is prime).
    return modPow(a, p-2, p);
}


ll modBinomial(ll n, ll k, ll p) {
// calculates C(n,k) mod p (assuming p is prime).

    ll numerator = 1; // n * (n-1) * ... * (n-k+1)
    for (ll i=0; i<k; i++) {
        numerator = (numerator * (n-i) ) % p;
    }

    ll denominator = 1; // k!
    for (ll i=1; i<=k; i++) {
        denominator = (denominator * i) % p;
    }

    // numerator / denominator mod p.
    return ( numerator* modInverse(denominator,p) ) % p;
}
     num of divisor and euler totient

ll phi[1000001],mark[1000001],divi[1000001];;
void divisorPhi(ll n)
{
    for(int i=1;i<=n;i++)
        phi[i]=i;
    for(int i=2;i<=n;i++)
    {
        if(!mark[i])
        {
            for(int j=i;j<=n;j+=i)
            {
                mark[j]=1;
                phi[j]*=(1-1/(double)i);
            }
        }
    }
    for(ll i=1;i<=n;i++)
    {
        for(ll j=i;j<=n;j+=i)
            divi[j]++;
    }
}
/* Precode Ends */
#define mod 1000000007
char A[1001][1001];
ll vis[1001][1001];
ll dis[1001][1001];
vector<ll>v;
map<ll,ll>myMap;
set<ll>mySet;
vector<pair<ll,ll> >vp;
priority_queue<ll> pq;
priority_queue<ll, vector<ll>, std::greater<ll> > first;
priority_queue<pair<ll,ll>,vector<pair<ll,ll>>,std::greater<pair<ll,ll>>>q;
ll po(ll a,ll n)
{
    ll ans=1;
    for(int i=1; i<=n; i++)
        ans*=a;
    return ans;
}

ll r,c;
void go(int i,int j)
{
    q.push(make_pair(i,j));
    vis[i][j]=1;
    dis[i][j]=0;
    while(!q.empty())
    {
        ll u=q.top().first;
        ll v=q.top().second;
        q.pop();
        for(int x=-2; x<=2; x++)
        {
            for(int y=-2; y<=2; y++)
            {
                //cout<<u+x<<" "<<v+y<<endl;
                if(u+x>r||u+x<1||v+y>c||v+y<1||(x==0&&y==0))
                    continue;
                if(vis[u+x][v+y]==0&&A[u+x][v+y]=='.')
                {
                    vis[u+x][v+y]=1;
                    if(abs(x)+abs(y)>1)
                        dis[u+x][v+y]=dis[u][v]+1;
                    else
                        dis[u+x][v+y]=dis[u][v];
                    q.push(make_pair(u+x,v+y));
                }
                else if(A[u+x][v+y]=='.')
                {
                    if((abs(x)+abs(y)>1)&&dis[u+x][v+y]>dis[u][v]+1)
                    {
                        dis[u+x][v+y]=dis[u][v]+1;
                        q.push(make_pair(u+x,v+y));
                    }
                    else if(dis[u][v]<dis[u+x][v+y]&&(abs(x)+abs(y)<=1))
                    {
                        dis[u+x][v+y]=dis[u][v];
                        q.push(make_pair(u+x,v+y));
                    }
                }
            }
        }
    }
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    ll sx,sy,dx,dy;
    string s;
    cin>>r>>c;
    cin>>sx>>sy;
    cin>>dx>>dy;
    for(int i=1; i<=r; i++)
    {
        cin>>s;
        for(int j=1; j<=c; j++)
        {
            A[i][j]=s[j-1];
            dis[i][j]=99999999999999;
        }
    }
    go(sx,sy);
//    for(int i=1; i<=r; i++)
//    {
//        for(int j=1; j<=c; j++)
//        {
//            // cout<<A[i][j]<<" ";
//            cout<<dis[i][j]<<" ";
//        }
//        cout<<endl;
//    }
    if(vis[dx][dy]==0)
    {
        cout<<-1<<endl;
    }
    else
    {
        cout<<dis[dx][dy]<<endl;
    }
    return 0;
}



Measured memory_bytes: 20348