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

int N,X[1005],Y[1005],nr,rez,k,egal;
double M[1000005];
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[++k]=m;
        }
    sort(M+1,M+1+k);
    M[0]=INF+1;
    for(int i=1;i<=k;i++)
    {
        if(M[i]==M[i-1])
            egal++;
        else
        {
            rez+=egal*(egal-1)/2;
            egal=1;
        }
    }
    rez+=egal*(egal-1)/2;
    fo<<rez<<'\n';
    return 0;
}