#include <bits/stdc++.h>

using namespace std;
typedef unsigned long long ull;
ifstream fin("trapez.in");
ofstream fout("trapez.out");

ull i,j,x,y,a,b,m,n,poz,rs;
long double tg[1000001],dbl;
struct coord
{
    int x,y;
}t[1001];

struct sincos
{
    int s,c;
}sc[1000001];

long double sinus(int a, int b)
{
    if ((t[a].y-t[b].y)==0) return -1;
    return (dbl*t[a].x-t[b].x)/(t[a].y-t[b].y);
}

int main()
{
    dbl=1;
    fin>>n;
    for (i=1;i<=n;i++)
        fin>>t[i].x>>t[i].y;
    for (i=1;i<=n;i++)
        for (j=i+1;j<=n;j++)
        tg[++poz]=sinus(i,j);
    sort(tg+1,tg+1+poz);
    for (i=2;i<=poz;i++)
        if (tg[i]==tg[i-1]) rs++;
    fout<<rs;
    return 0;
}