Hi.
I've found a formulae to solve this problem as the fastest variant,but still experiencing some minor problems with this task,cause I've got WA on the 2nd test...
I've also tried all the tests I found in this thread,the programme did the well...however,my problem doesn't disappear...
Could you please help me,give some more tests or so?

Do you handle the case where Horns + Hoofs can be < K

For example
2 2
10
The solution is
2.00
1 1

i think you did this like this::
x := TRUNC((a+1)/2);
y := TRUNC((b+1)/2);
you must write like this:
x := TRUNC((a+1)/2);
y := TRUNC(b/2);
i don't know why, but it help me!!!
good luck!