#include <fstream>
#include <map>
#define INF 2000000000
using namespace std;
ifstream fi("trapez.in");
ofstream fo("trapez.out");

int N,X[1005],Y[1005],nr,rez;
map <double,int> M;
map <double,int> :: iterator it;
double m,val;

int main()
{
    fi>>N;
    for(int i=1;i<=N;i++)
        fi>>X[i]>>Y[i];

    for(int i=1;i<=N;i++)
        for(int j=i+1;j<=N;j++)
        {
            if(Y[j]==Y[i])
                m=INF;
            else
                m=((double)(X[j]-X[i])/(double)(Y[j]-Y[i]));
            M[m]++;
        }

    for(it=M.begin();it!=M.end();it++)
    {
        nr=it->second;
        val=it->first;
        rez+=nr*(nr-1)/2;
    }
    fo<<rez<<'\n';
    return 0;
}