# Perfect Friends

easy

1. You are given a number n (representing the number of students). Each student will have an id from 0 to n - 1. 2. You are given a number k (representing the number of clubs) 3. In the next k lines, two numbers are given separated by a space. The numbers are ids of students belonging to same club. 4. You have to find in how many ways can we select a pair of students such that both students are from different clubs.

## Constraints

None

## Format

### Input

Input has been managed for you

### Output

Check the sample output

## Example

Sample Input

7
5
0 1
2 3
4 5
5 6
4 6

### Sample Output

16

Question Video