static void Main()
{
var(h, w) = Read2();
var sv = Read2() - new P(1, 1);
var ev = Read2() - new P(1, 1);
var s = Array.ConvertAll(new bool[h], _ => Console.ReadLine());
var r = GridShortestPath.UndirectedBfs(h, w, s, sv, ev);
Console.WriteLine(r.GetByP(ev));
}
static bool Solve()
{
var(h, w) = Read2();
var s = GridShortestPath.ReadEnclosedGrid(ref h, ref w);
var sv = GridShortestPath.FindChar(s, 's');
var ev = GridShortestPath.FindChar(s, 'g');
var r = GridShortestPath.UndirectedBfs(h, w, s, sv, ev);
return(r.GetByP(ev) < int.MaxValue);
}
