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Points: 3
Time limit: 1.0s
Memory limit: 256M

Problem type
Wcipeg 2017-2018 Test

The Carol Economy is a set of people who interact and share hearts (<3) 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.

Input Specification

The first line of input contains the integers N (1 \le N \le 1\,000) and K (0 \le K \le 10^{6}).

Output Specification

Output the number of new friendships that must be made. This number is guaranteed to be non-negative.

Sample Input

10 8

Sample Output



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