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

typedef struct
{
    double x,y;
} punct;

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

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]=(a[i].y-a[j].y)/(a[i].x-a[j].x);
    sort(b, b+(++poz));
    for (i=1; i<poz; i++)
        if (b[i]-b[i-1]<0.0001) nr++;
    g << nr;
    return 0;
}