#include<iostream>
#include<cstdio>
#include<cstring> 
#include<queue>

using namespace std;
const int maxn=100;
struct node {
    int x,y;
    int step; 
}S,T, Node;
int n,m;
char maze[maxn][maxn];
bool inq[maxn][maxn]= {false};
int X[4]= {0,0,1,-1};
int Y[4]= {1,-1,0,0};
bool test(int
 
 x,int y) {
    if(x>=n||x<0||y>=m||y<0)return false;
    if(maze[x][y]=='*')return false;
    if(inq[x][y]==true)return false;
    return true;
}
int BFS() {
    queue<node>q;
    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(test(newx,newy)) {
                Node.x=newx;
                Node.y=newy;
                Node.step=top.step+1;
                q.push(Node);
                inq[newx][newy]
 
=true;
            }
        }
    }
    return -1;
}
int main() {
    scanf("%d %d",&n,&m);

    for(int i=0; i<n; i++) {
        getchar();//過濾每行後的換行 
        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());
5 5
.....
.*.*.
.*S*.
.***.
...T*
2 2 4 3

    return 0;
}