#include <fstream>
#include <unordered_map>
using namespace std;

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

long long n,x[1000],y[1000];
unordered_map<double,long long>a;
int main()
{
    int i,j;long long s=0;
    cin>>n;
    for(i=0;i<n;i++){
        cin>>x[i]>>y[i];
        for(j=0;j<i;j++)
            s+=a[(double)(x[i]-x[j])/(y[i]-y[j])]++;
    }
    cout<<s;
}