#include <fstream>
#include <algorithm>

using namespace std;

ifstream cin("trapez.in");
ofstream cout("trapez.out");

short n, i, j;
int k, t, a, b, v, r;
float x[1001], y[1001], p[600001];
int main()
{
    cin>>n;
    for(i=1; i<=n; i++) cin>>x[i]>>y[i];
    for(i=1; i<n; i++)
        for(j=i+1; j<=n; j++)
        {
            ++k;
            if(y[i]-y[j]==0) k--, a++;
            else
                if(x[i]-x[j]==0) k--, b++;
                else p[k]=(y[i]-y[j])/(x[i]-x[j]);
        }
    t+=a*(a-1)/2+b*(b-1)/2;
    sort(p+1, p+k+1, greater<float>());
    i=1;
    while(i<=k)
    {
        v=p[i];
        i++;
        r=1;
        while(p[i]==v)
        {
            i++;
            r++;
        }
        t+=r*(r-1)/2;
    }
    cout<<t;
    return 0;
}