#include<bits/stdc++.h>
#define _LIBCPP_DEBUG 0
using namespace std;
typedef long long int ll;
ll MOD = 1e9 + 7;
int INF = 1 << 30;

vector<vector<char>> MAP(1004,vector<char>(1002,'#'));
vector<vector<int>> dist(1004,vector<int>(1002,INF));

int sy,sx,gy,gx;


void bfs(){
    queue<int> qR; qR.push(sy);
    queue<int> qC; qC.push(sx);

    dist[sy][sx]=0;
    int aR[4] = {1,0,-1,0};
    int aC[4] = {0,1,0,-1};
    while (!qR.empty()){
        int ROW=qR.front(); qR.pop();
        int COL=qC.front(); qC.pop();

        for (int i = 0; i < 4; ++i) {
            if(MAP[ROW+aR[i]][COL+aC[i]]!='#' && dist[ROW+aR[i]][COL+aC[i]]==INF){
                dist[ROW+aR[i]][COL+aC[i]] = dist[ROW][COL]+1;
                qR.push(ROW+aR[i]); qC.push(COL+aC[i]);
            }
        }

    }

}

int main(void){

    int R,C; cin>>R>>C;
    cin>>sy>>sx;
    cin>>gy>>gx;
    for (int i = 1; i <= R; ++i) {
        for (int j = 1; j <= C; ++j) {
            cin>>MAP[i][j];
        }
    }

    bfs();

    cout<<dist[gy][gx]<<endl;

    return 0;
}