#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(ll i = 0; i < (n); ++i)
#define repA(i, a, n) for(ll i = a; i < (n); ++i)
#define repD(i, a, n) for(ll i = a; i > (n); --i)
#define trav(a, x) for(auto& a : x)
#define all(x) x.begin(), x.end()
#define sz(x) (long long) (x).size()
#define fill(a) memset(a, 0, sizeof(a))
#define fst first
#define snd second
// #define mp make_pair
#define pb push_back
void __print(int x) {cout << x;}
void __print(long x) {cout << x;}
void __print(long long x) {cout << x;}
void __print(unsigned x) {cout << x;}
void __print(unsigned long x) {cout << x;}
void __print(unsigned long long x) {cout << x;}
void __print(float x) {cout << x;}
void __print(double x) {cout << x;}
void __print(long double x) {cout << x;}
void __print(char x) {cout << '\'' << x << '\'';}
void __print(const char *x) {cout << '\"' << x << '\"';}
void __print(const string &x) {cout << '\"' << x << '\"';}
void __print(bool x) {cout << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cout << '{'; __print(x.first); cout << ','; __print(x.second); cout << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cout << '{'; for (auto &i: x) cout << (f++ ? "," : ""), __print(i); cout << "}";}
void _print() {cout << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cout << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define dbg(x...) cout << "[" << #x << "] = ["; _print(x)
#else
#define dbg(x...)
#endif
const long double PI = 3.141592653589793238462643383;
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<long long int> vll;
typedef vector<double> vd;
typedef vector<pii> vii;
long long Ceil(long long a, long long b){
    if(a%b==0) return a/b;
    else return (a/b)+1;
}
ll p=1000000007;
float E = 0.00000000000001;
ll power(ll x, ll y){
    if(y==0){
        return 1;
    }
    if(y%2==0){
        ll q=power(x,y/2);
        q=q%p;
        return (q*q)%p;
    }
    ll q=power(x,y/2);
    q=q%p;
    return ((x%p)*((q*q)%p))%p; 
}
bool isPowerOfTwo (long long x)  
{  
    /* First x in the below expression is for the case when x is 0 */
    return x && (!(x&(x-1)));  
}  

long long int gcd(long long int a, long long int b){ 
    if (a == 0) 
        return b;  
    return gcd(b % a, a); 
}
long long int mod(long long int a, long long int b) {
    long long int ret = a%b; return ret>=0? ret: ret+b; 
}
bool proper(int i, int j, int n, int m){
    return i>=0 && j>=0 && i<n && j<m;
}
void dfs_visit(int i, int j, vector <string> &vec, vector <vector<int>> &visited, vector <vector<int>> &ids, int id){
    if(!proper(i, j, vec.size(), vec[0].size()) || vec[i][j] == '#' || visited[i][j])
        return;
    visited[i][j] = 1;
    ids[i][j] = id;
    dfs_visit(i+1, j, vec, visited, ids, id);
    dfs_visit(i-1, j, vec, visited, ids, id);
    dfs_visit(i, j+1, vec, visited, ids, id);
    dfs_visit(i, j-1, vec, visited, ids, id);
}
int main(){
    std::ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);   
    freopen("output.txt", "w", stdout);
    #endif
    int t = 1;
    // cin>>t;
    while(t--){ 
        int h,w,ch,cw,dh,dw;cin>>h>>w>>ch>>cw>>dh>>dw;
        ch--;cw--;dh--;dw--;
        vector<string> vec(h);
        for(int i = 0 ; i < h ; i++){
            string s;cin>>s;
            vec[i] = s;
        }
        vector <vector<int>> visited(h, vector<int>(w, 0));
        vector <vector<int>> ids(h, vector<int>(w, -1));
        int count = 0; 
        for(int i = 0 ; i < h ; i++){
            for(int j = 0 ; j < w ; j++){
                if(!visited[i][j] && vec[i][j] != '#'){
                    dfs_visit(i, j, vec, visited, ids, count);
                    count++;
                }
            }
        }
        // dbg(ids);
        // dbg(count);
        // vector <unordered_set<int>> adj(count);
        // vector<vector<int>> adj2(count);
        vector<vector<int>> adj(count);
        for(int i = 0 ; i < h ; i++){
            for(int j = 0 ; j < w ; j++){
                if(vec[i][j] == '#')
                    continue;
                for(int k = -2 ; k <= 2 ; k++){
                    for(int l = -2 ; l <= 2 ; l++){
                        if(!proper(i+k,j+l,h,w) || vec[i+k][j+l] == '#' || ids[i+k][j+l] == ids[i][j])
                            continue;
                        // dbg(ids[i][j]);
                        // adj[ids[i][j]].insert(ids[i+k][j+l]);
                        // adj[1].insert(ids[i+k][j+l]);
                        // adj2[ids[i][j]].push_back(ids[i+k][j+l]);
                        adj[ids[i][j]].push_back(ids[i+k][j+l]);
                    }
                }
            }
        }
        // dbg(adj);
        // vector <unordered_set<int>> adj(count);
        // for(int i = 0 ; i < count ; i++){
            // unordered_set<int> s(adj2[i].begin(), adj2[i].end());
            // adj[i] = s;
            // adj[i] = unordered_set<int>(adj2[i].begin(), adj2[i].end());
        // }
        int src = ids[ch][cw], dest = ids[dh][dw];
        queue<int> q;
        q.push(src);
        if(src == dest){
            cout<<0<<endl;
            continue;
        }
        int ans = 0;
        vector <int> visited2(count, 0);
        while(!q.empty()){  
            int sz = q.size();
            ans++;
            for(int i = 0 ; i < sz ; i++){
                int node = q.front();
                q.pop();
                if(visited2[node])
                    continue;
                visited2[node] = 1;
                for(auto &x:adj[node]){
                    if(x == dest){
                        cout<<ans<<endl;
                        return 0;
                    }
                    q.push(x);
                }
            }
        }
        cout<<-1<<endl;
    }
    return 0;
}


Measured memory_bytes: 25440