#include <cstdio>
#include <algorithm>
#include <vector>
#include <cmath>

using namespace std;
const double eps=1.e-14;
const double INF=2.e-9;
struct POINT
{
    double x,y;
};
double dist(POINT A, POINT B)
{
    return sqrt((B.x-A.x)*(B.x-A.x)+(B.y-A.y)*(B.y-A.y));
}
bool vertical(POINT A,POINT B)
{
    return (fabs(A.x-B.x)<eps);
}
bool same_point (POINT A,POINT B)
{
    return fabs(A.x-B.x)<eps&&fabs(A.y-B.y)<eps;
}
double panta (POINT A,POINT B)
{
    if(vertical(A,B))
        return INF;
    return (B.y-A.y)/(B.x-A.x);
}
vector <POINT>v;
vector <double>pante;
POINT aux;
int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    int n,i,a,b,j,k=0,num=0,cnt;
    double pan,old;
    scanf("%d",&n);
    for(i=1;i<=n;++i)
    {
        scanf("%d %d",&a,&b);
        aux.x=a;
        aux.y=b;
        v.push_back(aux);
    }
    for(i=0;i<n-1;++i)
    {
        for(j=i+1;j<n;++j)
        {
            pan=panta(v[i],v[j]);
            pante.push_back(pan);
        }
    }
    sort(pante.begin(),pante.end());
    i=num=cnt=0;
    old=-1;
    while(i<pante.size())
    {
        if(fabs(pante[i]-old)<eps)
        {
            i++;
            cnt++;
        }
        else
        {
            k+=1LL*cnt*(cnt-1)/2;
            cnt=1;old=pante[i];++i;
        }
    }
    k+=1LL*cnt*(cnt-1)/2;
    printf("%d",k);
    return 0;
}