#include <iostream>
#include <algorithm>
#include <complex>
#include <utility>
#include <vector>
#include <string>
#include <queue>
#include <tuple>
#include <cmath>
#include <bitset>
#include <cctype>
#include <set>
#include <numeric>
#include <functional>
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(ll i=ll(a);i<ll(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define all(x) (x).begin(),(x).end()
#define PRINT(V) cout << V << "\n"
#define SORT(V) sort((V).begin(),(V).end())
#define RSORT(V) sort((V).rbegin(), (V).rend())
using namespace std;
using ll = long long;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
inline void Yes(bool condition){ if(condition) PRINT("Yes"); else PRINT("No"); }
template<class itr> void cins(itr first,itr last){
    for (auto i = first;i != last;i++){
        cin >> (*i);
    }
}
template<class itr> void array_output(itr start,itr goal){
    string ans = "",k = " ";
    for (auto i = start;i != goal;i++) ans += to_string(*i)+k;
    if (!ans.empty()) ans.pop_back();
    PRINT(ans);
}
ll gcd(ll a, ll b) {
    return a ? gcd(b%a,a) : b;
}
const ll INF = 1e17;
const ll MOD = 1000000007;
typedef pair<ll,ll> P;
const ll MAX = 1005;
constexpr ll nx[4] = {1,0,-1,0};
constexpr ll ny[4] = {0,1,0,-1};
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll r,c;
    cin >> r >> c;
    ll sx,sy,gx,gy;
    cin >> sx >> sy >> gx >> gy;
    vector<string> grid(r);
    vector<vector<ll>> ans(r,vector<ll>(c,INF));
    vector<vector<bool>> done(r,vector<bool>(c,0));
    rep(i,r) cin >> grid[i];
    queue<P> q;
    ans[sx-1][sy-1] = 0;
    q.push(P(sx-1,sy-1));
    while(!q.empty()){
        ll x,y;
        tie(x,y) = q.front();
        done[x][y] = 1;
        q.pop();
        rep(i,4){
            ll xn = x+nx[i],yn = y+ny[i];
            if (xn >= 0 && xn < r && yn >= 0 && yn < c && grid[xn][yn] == '.' && done[xn][yn] == 0){
                chmin(ans[xn][yn],ans[x][y]+1);
                done[xn][yn] = 1;
                q.push(P(xn,yn));
            }
        }
    }
    PRINT(ans[gx-1][gy-1]);
}