#include <cstdio>
#include <map>

using namespace std;

pair<int, int>p[1005];
pair<int, int>pa;

int n, s;

/**struct panta
{
    int numarator, numitor;
}pa;**/

map<pair<int, int>, int> fr;

int cmmdc(int x, int y)
{
    if(y==0)
        return x;
    cmmdc(y, x%y);
}

int rez(int n)
{
    return n*(n-1)/2;
}

int main()
{
    freopen("trapez.in", "r", stdin);
    freopen("trapez.out", "w", stdout);

    scanf("%d", &n);
    for(int i=1;i<=n;i++)
    {
        int x, y;
        scanf("%d %d", &p[i].first, &p[i].second);
        //int diviz=cmmdc(x, y);
        //pa.numarator=x/diviz;
        //pa.numitor=y/diviz;
        //fr[{x, y}]++;
    }

    for(int i=1;i<n;i++)
        for(int j=i+1;j<=n;j++)
        {
            pa.first=p[j].second-p[i].second;
            pa.second=p[j].first-p[i].first;
            int diviz=cmmdc(pa.first, pa.second);
            pa.first/=diviz;
            pa.second/=diviz;
            //printf("%d %d\n", pa.first, pa.second);
            fr[{pa.first, pa.second}]++;
        }

    for(auto i:fr)
    {
        s+=rez(i.second);
    }
    printf("%d", s);

    return 0;
}