//#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream cin("trapez.in");
ofstream cout("trapez.out");

struct Point{
    int x,y;
}v[1005];
double dre[1005*1005];
int contor=0;
int main()
{
    int n,paralel=0;
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>v[i].x>>v[i].y;
    }
    for(int i=1;i<=n;i++){
        for(int j=i+1;j<=n;j++){
            int d1=v[i].x-v[j].x;
            int d2=v[i].y-v[j].y;
            if(d2==0){
                paralel++;
            }
            else{
                double rap=(double)(d1)/(double)(d2);
                dre[++contor]=rap;
                /*if(um.find(rap)==um.end()){
                    um[rap]=1;
                }
                else
                    um[rap]++;
                    */
            }
        }
    }
    sort(dre+1,dre+contor+1);
    int raspuns=0,cont=0;
    for(int i=1;i<=contor;i++){
        if(dre[i]!=dre[i-1]){
            raspuns+=cont*(cont-1)/2;
            cont=0;
        }
        cont++;
    }
    raspuns+=cont*(cont-1)/2;
    raspuns+=paralel*(paralel-1)/2;
    cout<<raspuns;
    return 0;
}