static void Main()
{
var(h, w) = Read2();
var(ti, tj) = Read2();
var sv = (ti - 1, tj - 1);
(ti, tj) = Read2();
var gv = (ti - 1, tj - 1);
var c = Array.ConvertAll(new bool[h], _ => Console.ReadLine());
var dp = new DP2 <int>(h, w, MergeOp.Min(1 << 30));
dp[sv] = 0;
dp.AddTransition(p =>
{
if (c[p.i][p.j] == '#')
{
return;
}
var nv = p.Value + 1;
p.Move(-1, 0).Merge(nv);
p.Move(1, 0).Merge(nv);
p.Move(0, -1).Merge(nv);
p.Move(0, 1).Merge(nv);
});
for (int k = 0; k < h * w; k++)
{
dp.Execute(0, h, 0, w);
}
Console.WriteLine(dp[gv]);
}
protected ShapeV2(DP2 dp2)
{
_dp2 = dp2;
}
public DrowingAdapterV2()
{
_dp1 = new DP2();
}
public RectangularV2(DP2 dp2)
{
this.dp2 = dp2;
}
public P(int _i, int _j, DP2 <T> _dp)
{
i = _i; j = _j; dp = _dp;
}