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

using namespace std;
const double eps=1.e-14;
const double INF=2000000000;
struct POINT
{
    int x,y;
};
double dist(POINT a,POINT b)
{
    return sqrt((a.y-b.y)*(a.x-b.x)+(a.x-b.x)*(a.y-b.y));
}
double panta(POINT a,POINT b)
{
    if(a.x==b.x)
        return INF;
    else
        return (1.0*b.y-a.y)/(b.x-a.x);
}
vector<POINT> temp;
vector<double> v;
int nap(double k)
{
    int i,a=0;
    for(i=1;i<=v.size();i++)
        if(v[i]==k)a++;
    return a;
}
long long inm(int a,int b)
{
    int p=1,i;
    for(i=a;i<=b;i++)
        p*=i;
    return p;
}
int comb(int n,int k)
{
    return inm(k,n)/inm(1,k);
}

int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    int i,j,n,k=0,prev=-1,s=0;
    POINT p;
    scanf("%d", &n);
    for(i=1;i<=n;i++)
    {
        scanf("%d%d", &p.x,&p.y);
        temp.push_back(p);
    }
    for(i=1;i<=n-1;i++)
    {
        for(j=i+1;j<=n;j++)
        {
            v.push_back(panta(temp[i],temp[j]));
        }
    }
    sort(v.begin(),v.end());
    for(i=1;i<v.size();)
    {
        if(nap(v[i])>1)
            s+=comb(nap(v[i]),2);
        i+=nap(v[i]);
    }
    printf("%d\n", s);
    return 0;
}