#include<iostream>
#include<fstream>
using namespace std;
ifstream fin("trapez.in");
ofstream fout("trapez.out");
int n,i,nrt,dim;
double panta[1000001];

struct xoy{
    double x,y;
};
xoy V[1001];

void pan(xoy a,xoy b)
{
    if(a.x==b.x)
        panta[++dim]=-1;
    else
    {
        dim++;
        panta[dim]=(double)(a.y-b.y)/(double)(a.x-b.x);
    }
}

int main()
{
    fin>>n;
    for(i=1; i<=n; i++)
        fin>>V[i].x>>V[i].y;
    int j=0;
    for(i=1; i<=n; i++)
        for(j=i+1; j<=n; j++)
            pan(V[i],V[j]);
    for(i=1; i<=dim; i++)
    {
        //cout<<panta[i]<<"\n";
        for(j=i+1; j<=dim; j++)
            if(panta[i]==panta[j])
                nrt++;
    }
    fout<<nrt<<"\n";
    fin.close();
    fout.close();
    return 0;
}