#include<bits/stdc++.h>

using namespace std;

int n, m;
int ans[1000][1000];
char arr[1000][1000];

void dfs(int posX, int posY, int prev)
{
    if(posX >= n || posY >= m || posX < 0 || posY < 0)
        return;
    if(arr[posX][posY] == '#')
        return;
    if(ans[posX][posY] < prev + 1)
        return;
    ans[posX][posY] = prev + 1;

    dfs(posX + 1, posY, prev + 1);
    dfs(posX - 1, posY, prev + 1);
    dfs(posX, posY + 1, prev + 1);
    dfs(posX, posY - 1, prev + 1);
}

int main()
{
    cin >> n >> m;
    for(int i = 0; i < n; i++)
        for(int j = 0; j < m; j++)
        {
            cin >> arr[i][j];
            ans[i][j] = INT_MAX;
        }
    int aX, aY, bX, bY;
    cin >> aX >> aY >> bX >> bY;
    dfs(aX, aY, 0);
    ans[bX][bY] == INT_MAX ? cout << 0 : cout << ans[bX][bY];
}