I'm getting WA on 13th test.
   What's wrong with that test?
   I urgently need help. At least, I amnot getting TL.

By the way, are there only 3 banknotes? Maybe test is not correct. And according to conditions of this problem, a number of some of them should be >= ( n / 2 ) if n = even;
and > (n + 1) / 2 if n = odd. Is it right?