Wcipeg 2017-2018 Test
The Carol Economy is a set of people who interact and share hearts (
with each other. In order to be part of the Carol Economy, each person
must be friends with every other person. Carol is trying to set up a
larger Carol economy between some of her friends. There are ~N~ people,
and ~K~ pairs of people know each other. Help Carol calculate the amount
of new friendships that must be made.
The first line of input contains the integers ~N~ ~(1 \le N \le 1\,000)~ and ~K~ ~(0 \le K \le 10^6)~.
Output the number of new friendships that must be made. This number is guaranteed to be non-negative.