#include<fstream>
#include<algorithm>
#define inf 0x3f3f3f3f
using namespace std;

ifstream cin("trapez.in");
ofstream cout("trapez.out");
const int nmax=1005;

int x[nmax],y[nmax];
int n,i,j,k=0;
double panta[nmax];
int res=0;

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++)
        panta[++k]=(x[i]==x[j])?inf : (double)(y[j]-y[i])/(x[j]-x[i]);
    sort(panta+1,panta+k+1);
    int nr=0;
    for (i=2;i<=k;i++) if (panta[i]==panta[i-1]) ++nr,res+=nr;
       else nr=0;
    cout<<res;
    return  0;
}