#include <fstream>
#include <algorithm>
using namespace std;

typedef struct
{
    long x,y;
} punct;

typedef struct
{
    long long numarator, numitor;
} panta;

panta b[1100000];
int n,poz=-1,nr=0;
punct a[1100];

bool ok(panta a, panta b)
{
    return (a.numitor*b.numarator==a.numarator*b.numitor);
}

int main()
{
    ifstream f("trapez.in");
    ofstream g("trapez.out");
    f >> n;
    int i,j;
    for (i=0; i<n; i++)
        f >> a[i].x >> a[i].y;
    for (i=0; i<n-1; i++)
    for (j=i+1; j<n; j++)
    {
        b[++poz].numarator=a[i].y-a[j].y;
        b[poz].numitor=a[i].x-a[j].x;
    }
    sort(b, b+(++poz),ok);
    for (i=1; i<poz; i++)
        if (b[i].numitor*b[i+1].numarator==b[i].numarator*b[i+1].numitor) nr++;
    g << nr;
    return 0;
}