#include <cstdio>
#include <vector>
#include <algorithm>
#define eps 1e-12
using namespace std;
double panta[1000010];
vector <pair <int,int> >v;
int n,i,x,y,nr,nr2,j;
long long sol;
int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    scanf("%d\n",&n);
    for(i=1; i<=n; ++i)
    {
        scanf("%d %d\n",&x,&y);
        v.push_back(make_pair(x,y));
    }
    for(i=0; i<n-1; ++i)
        for(j=i+1; j<n; ++j)
        {
            if(v[i].first-v[j].first!=0)
                panta[++nr]=(double)(v[i].second-v[j].second)/(v[i].first-v[j].first);
            else panta[++nr]=2000000001;
        }
    sort(panta+1,panta+nr+1);
    i=2;
    while(i<=nr)
    {
        nr2=1;
        while(panta[i]-panta[i-1]<eps && panta[i]-panta[i-1]>-eps)
        {
            ++i;
            ++nr2;
        }
        sol+=nr2*(nr2-1)/2;
        if(nr2==1)
            ++i;
    }
    printf("%lld\n",sol);

    return 0;
}