Points: 7 (partial)
Time limit: 1.0s
Memory limit: 64M
Winnie has fallen in love with the people from the K-pop band group: BTS. In this group, there are people. Her love for each person can be modeled as a line of the form , with representing time, and representing her affection for the person.
You want to know, how many pairs of people will receive the same amount of affection from Winnie at a common point in time (including negative time)?
The first line will contain the integer , the number of people.
The next lines will each contain two integers, .
Output the number of pairs of people that will receive the same amount of affection from Winnie at a common point in time.
Subtask 1 [10%]
Subtask 2 [90%]
No additional constraints.
4 1 3 2 3 0 2 1 2