#include<queue>
#include<cstring>
#include<cstdio>
using namespace std;
int X[4]={0,0,1,-1};
int Y[4]={1,-1,0,0};
int n,m;
char maze[1000][1000];
bool inq[1000][1000]={false};
struct node
{
    int x,y;
    int step;
}s,T,nodes;
bool judge(int x,int y)
{
    if(x<0||x>=n||y<0||y>=m)
        return false;
    if(maze[x][y]=='*')
        return false;
    if(inq[x][y]==true)
        return false;
    return true;
}
int bfs() {
    queue<node> q;
    //s.x=x;
    //s.y=y;
    q.push(s);
    while (!q.empty()) {
        node top = q.front();
        q.pop();
        if (top.x == T.x && top.y == T.y)
            return top.step;
        for (int i = 0; i < 4; i++) {

                int newx = top.x + X[i];
                int newy = top.y + Y[i];
                if (judge(newx, newy)) {
                    nodes.x = newx;
                    nodes.y = newy;
                    nodes.step = top.step + 1;
                    q.push(nodes);
                    inq[newx][newy] = true;

                }
            }
        }
        return -1;
    }

    int main()
    {
        //int n, m;
        scanf("%d%d", &n, &m);
        // getchar();
        for (int i = 0; i < n; i++) {
            getchar();
            for (int j = 0; j < m; j++) {
                maze[i][j] = getchar();
            }
            maze[i][m + 1] = '\0';
        }
        scanf("%d%d%d%d", &s.x, &s.y, &T.x, &T.y);
        s.step = 0;
        printf("%d\n", bfs());
        return 0;
    }