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  1. Prepare
  2. Algorithms
  3. Graph Theory
  4. Journey to the Moon

Journey to the Moon

The member states of the UN are planning to send people to the moon. They want them to be from different countries. You will be given a list of pairs of astronaut ID's. Each pair is made of astronauts from the same country. Determine how many pairs of astronauts from different countries they can choose from.

Example


There are astronauts numbered through . Astronauts grouped by country are and . There are pairs to choose from: and .

Function Description

Complete the journeyToMoon function in the editor below.

journeyToMoon has the following parameter(s):

  • int n: the number of astronauts
  • int astronaut[p][2]: each element is a element array that represents the ID's of two astronauts from the same country

Returns
- int: the number of valid pairs

Input Format

The first line contains two integers and , the number of astronauts and the number of pairs.
Each of the next lines contains space-separated integers denoting astronaut ID's of two who share the same nationality.

Constraints

Sample Input 0

5 3
0 1
2 3
0 4

Sample Output 0

6

Explanation 0

Persons numbered belong to one country, and those numbered belong to another. The UN has ways of choosing a pair:

Sample Input 1

4 1
0 2

Sample Output 1

5

Explanation 1

Persons numbered belong to the same country, but persons and don't share countries with anyone else. The UN has ways of choosing a pair: