#include <cstdio>
using namespace std;
struct punct
{
    double x;
    double y
};
double xi,yi,xf,yf,d;
int nrt;
punct a[1501];
bool cmp(punct a, punct b)
{
    if (a.x<b.x) return true;
    else
    {
        if (a.x>b.x) return false;
        else
        {
            if (a.y<b.y) return true;
            else return false;
        }
    }
}
int cautare_binara(int xf, int yf, int j)
{
    int st=j+1;
    int dr=n;
    int mij=(st+dr)/2;
    while (a[mij].x!=xf && a[mij].y!=yf && st<=dr)
    {
        if (a[mij].x>xf) mij=dr-1;
        else if (a[mij]<xf) mij=st+1;
        else
        {
            if (a[mij].y>yf) mij=dr-1;
            else if (a[mij]<yf) mij=st+1;
        }
    }
}
int main()
{
    freopen("triang.in","r",stdin);
    freopen("triang.out","w",stdout);
    scanf("%d\n",&n);
    nrt=0;
    for (i=1; i<=n; i++) scanf("%llf %llf\n",&a[i].x,&a[i].y);
    sort(a+1,a+n+1,cmp);
    for (i=1; i<=n-2; i++) for (j=i+1; j<=n-1; j++)
        {
            xi=(a[j].x-a[i].x)/2+sqrt(1.0*3)(a[j].y-a[i].y)/2;
            yi=(a[j].y-a[i].y)/2-sqrt(1.0*3)(a[j].x-a[i].x)/2;
            d=sqrt(1.0*(a[j].x-a[i].x)*(a[j].x-a[i].x)+1.0*(a[j].y-a[i].y)*(a[j].y-a[i].y));
            xf=xi*d+a[i].x;
            yf=yi*d+a[i].y;
            if (cautare_binara(xf,yf,j)!=-1) nrt++;
        }
    return 0;
}