#include <cstdio>
#include <algorithm>
#include <cmath>
#define eps 0.00001
#define nmax 1005
using namespace std;
double v[nmax*nmax/2];
int n,m,tot;
long long sol;
int x[nmax],y[nmax];

int main()
{
    int i,j;
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    scanf("%d",&n);
    for (i=1;i<=n;i++)
        scanf("%d %d",&x[i],&y[i]);
    for (i=1;i<n;i++)
        for (j=i+1;j<=n;j++)
            if (x[i]!=x[j])
                v[++m]=1.0*(y[j]-y[i])/(x[j]-x[i]);
            else
                v[++m]=1<<30;
    sort(v+1,v+m+1);
    for (i=1;i<=m;i=j+1) {
        j=i;
        while (j<=m&&abs(v[i]-v[j+1])<eps)
            j++;
        tot=j-i+1;
        sol+=(tot*(tot-1))>>1;
        i=j+1;
    }
    printf("%lld",sol);
    return 0;
}