#include<fstream>
#include<algorithm>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
struct data{
    int x,y;
}a[1005];
double v[1000000];
int main()
{
    int n,i,k=0,j,nr=0;
    f>>n;
    for(i=1;i<=n;++i)
       {f>>a[i].x;
        f>>a[i].y;}
    for(i=1;i<n;i++)
        for(j=i+1;j<=n;j++)
            {if(a[j].x-a[i].x!=0)v[++k]=float(a[j].y-a[i].y)/(a[j].x-a[i].x);
             else if(a[j].y-a[i].y!=0)v[++k]=float(a[j].x-a[i].x)/(a[j].y-a[i].y);}
     sort(v+1,v+n+1);
    for(i=1;i<k;i++)
        if(v[i]==v[i+1])nr++;
    g<<nr;
    return 0;
}