#include <bits/stdc++.h>
#define nmax 1003
#define dif 1e-8

using namespace std;

ifstream fin ("trapez.in");
ofstream fout ("trapez.out");

pair<int, int> v[nmax];
double V[nmax*nmax];

int n,k,sum;

int main()
{
    fin>>n;
    for(int i=1;i<=n;++i)
        fin>>v[i].first>>v[i].second;
    for(int i=1;i<=n;++i)
        for(int j=i+1;j<=n;++j){
            if(v[i].first==v[j].first){
                V[++k]=DBL_MAX;
                continue;
            }
            V[++k]=(double)(v[i].second-v[j].second)/(double)(v[i].first-v[j].first);
            //if(v[i].first<v[j].first)V[k]=-V[k];
        }
    sort(V+1,V+k+1);
    for(int i=1;i<=k;++i){
        int j=i;
        while(abs(V[i]-V[i+1])<dif)
            ++i;
        sum+=(i-j)*(i-j+1)/2;
    }
    fout<<sum<<'\n';
    return 0;
}