static void Main(string[] args)
{
int[] rc = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
int[] syx = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
int[] gyx = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
for (int i = 0; i < rc[0]; i++)
{
List <BlockClass> tmpList = new List <BlockClass>();
Maze.Add(tmpList);
string line = Console.ReadLine();
for (int j = 0; j < rc[1]; j++)
{
BlockClass tmpBlock = new BlockClass();
tmpList.Add(tmpBlock);
tmpBlock.x = i;
tmpBlock.y = j;
if (line[j] == '.')
{
tmpBlock.isRoad = true;
}
else
{
tmpBlock.isRoad = false;
}
}
}
Maze[gyx[0] - 1][gyx[1] - 1].isGoal = true;
Maze[syx[0] - 1][syx[1] - 1].Min = 0;
Queue.Add(Maze[syx[0]][syx[1]]);
BFS(syx[0] - 1, syx[1] - 1);
//
}
static void Main(string[] args)
{
int[] hw = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
List <BlockClass> list0 = new List <BlockClass>();
Maze.Add(list0);
for (int i = 0; i < hw[1] + 2; i++)
{
BlockClass tmpBlock = new BlockClass();
list0.Add(tmpBlock);
tmpBlock.x = 0;
tmpBlock.y = i;
tmpBlock.isRoad = false;
}
for (int i = 1; i <= hw[0]; i++)
{
List <BlockClass> tmpList = new List <BlockClass>();
Maze.Add(tmpList);
string line = Console.ReadLine();
line = "#" + line + "#";
for (int j = 0; j <= hw[1] + 1; j++)
{
BlockClass tmpBlock = new BlockClass();
tmpList.Add(tmpBlock);
tmpBlock.x = i;
tmpBlock.y = j;
if (line[j] == '.')
{
tmpBlock.isRoad = true; counter++;
}
else
{
tmpBlock.isRoad = false;
}
}
}
List <BlockClass> listlist = new List <BlockClass>();
Maze.Add(listlist);
for (int i = 0; i < hw[1] + 2; i++)
{
BlockClass tmpBlock = new BlockClass();
listlist.Add(tmpBlock);
tmpBlock.x = hw[0] + 1;
tmpBlock.y = i;
tmpBlock.isRoad = false;
}
Maze[hw[0]][hw[1]].isGoal = true;
Maze[1][1].Min = 0;
Queue.Add(Maze[1][1]);
BFS(1, 1);
if (Maze[hw[0]][hw[1]].Min == -1)
{
Console.WriteLine(-1);
}
else
{
Console.WriteLine(counter - Maze[hw[0]][hw[1]].Min - 1);
}
//
}