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
5 3
0 1
2 3
0 4
Sample Output
6
Explanation
Persons numbered , and belong to the same country, and those numbered and belong to the same country, but different from the previous one. All in all, the UN has ways of choosing a pair:
- persons and
- persons and
- persons and
- persons and
- persons and
- persons and