#include <bits/stdc++.h>
using namespace std;
const int N = 50;
struct NODE
{
	int x, y, step;
} que[N * N];
int front, rear, r, c, x_1, x_2, y_1, y_2, vis[N][N];
int g[N][N];
int dx[5] = { 0, -1, 1, 0, 0 };
int dy[5] = { 0, 0, 0, 1, -1 };
void BFS( int x, int y )
{
	vis[x][y] = 1;
	NODE temp = { x, y, 0 };
	que[rear++] = temp;
	while ( rear > front )
	{
		if ( que[front].x == x_2 && que[front].y == y_2 )
		{
			cout << que[front].step;
			return ;
		}
		for ( int i = 1; i <= 4; i++ )
		{
			int tx = que[front].x + dx[i];
			int ty = que[front].y + dy[i];
			if ( tx < 1 || tx > r || ty < 1 || ty > c )
			{
				continue;
			}
			if ( g[tx][ty] == '.' && vis[tx][ty] == 0 )
			{
				NODE temp = { tx, ty, que[front].step + 1 };
				que[rear++] = temp;
				vis[tx][ty] = 1;
			}
		}
		front++;
	}
		
}
int main() 
{
	cin >> r >> c;
	for ( int i = 1; i <= r; i++ )
	{
		for ( int j = 1; j <= c; j++ )
		{
			cin >> g[i][j];
		}
	}
	cin >> x_1 >> y_1 >> x_2 >> y_2;
	BFS( x_1, y_1 );
	return 0;
}