3 3
1 2
2 3
3 1
1 3
how is this possible?
from 1 to 2 there is an uphill road...from 2 to 3 there is also an uphill road...then how can there be a uphill road from 3 to 1??from 3 to 1 there should be a downhill road...
correct me if i am wrong..

Don't worry about that, it's just an example and the contraints don't say nothing about.