#include <stdio.h>
#include <algorithm>
using namespace std;

const int  INF = 2100000;

struct puncte
{
    int x, y;
}v[1001];

double p[1000 * 1000 + 1];
int nr = 0;

double abs(double  x)
{
    if( x < 0)
        return -x;
    else
        return x;
}

double calcPanta(int x1, int y1, int x2, int y2)
{
    if(x1 == x2)
        return INF;
    else
    {
        double val = 1.00 * (y2 - y1)/(x2 - x1);
        //val = abs(val);
        return val;
    }
}

int main()
{
    FILE *fin, *fout;

    fin = fopen("trapez.in", "r");
    fout = fopen("trapez.out", "w");

    int n;

    fscanf(fin, "%d", &n);

    for(int i = 1; i <= n; i++)
        fscanf(fin, "%d %d", &v[i].x, &v[i].y);

    for(int i = 1; i <= n; i++)
    {
        for(int j = i + 1; j <= n; j++)
            p[++nr] = calcPanta(v[i].x, v[i].y, v[j].x, v[j].y);
    }

    sort(&p[1], &p[nr + 1]);

    int cnt = 0;

    for(int i = 2; i <= nr; i++)
    {
        if(p[i] - p[i - 1] <=0.000000000001)
            cnt++;
    }

    fprintf(fout, "%d", cnt);

    return 0;
}