I cann't understand why WA#10. Must I use long double? Please, give me some terrible tests.

I got WA on test 10 too. And it's a little bit strange because the algo is simple. Maybe there are some problems with "10 fractional digits"...

0-result must be established in int64 only
use 6 permutations for vertices of aim triangle also

long double won't help because it's same type as double in VC++

As for 6 permutations, I think there must be only 3. Otherwise we'll consider flip-overs.

long double4 is normal.
Use EPS = 0.00000001; if use EPS = 0.00000000001 then get WA11.