#include<bits/stdc++.h>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
double p[1000001];
int n,m,i,j,s,x[1001],y[1001];
int main()
{
    for(f>>n,i=1;i<=n;++i)
        f>>x[i]>>y[i];
    for(i=1;i<=n;++i)
        for(j=i+1;j<=n;++j)
            p[++m]=1.0*(x[i]-x[j])/(y[i]-y[j]);
    for(sort(p+1,p+m+1),i=1;i<=m;++i) {
        for(j=1;p[i]==p[i+1]&&i+1<=m;++j,++i);
        s+=(j-1)*j/2;
    }
    g<<s;
    return 0;
}