#include <fstream>
#include <cmath>
#include <map>
using namespace std;
ifstream in("trapez.in");
ofstream out("trapez.out");
map <double,double> ma;
double n,su1,su2,sum,x[1005],y[1005],zer;
int i,j;
int main()
{
in>>n;
for (i=1;i<=n;++i)
{
    in>>x[i]>>y[i];
}
for (i=1;i<=n;++i)
    for (j=i+1;j<=n;++j)
{
    su1=y[j]-y[i];
    su2=x[j]-x[i];
    if (su2==0) {zer++; sum=sum+zer-1;}
    else {ma[su1/su2]++;
    sum=sum+(ma[su1/su2]-1);}
}
out<<sum;
    return 0;
}