#include <bits/stdc++.h>

using namespace std;

ifstream in("trapez.in");
ofstream out("trapez.out");

int n;
struct point{int x,y;};
point *points;
struct line{point A,B;};
line *lines;
int u = 0;
int nr = 0;

bool m_line(line l1,line l2)
{
    if((l1.B.y-l1.A.y)*(l2.B.x - l2.A.x) == (l2.B.y-l2.A.y)*(l1.B.x - l1.A.x))
        return true;
    return false;
}

int main()
{
    in>>n;
    points = new point[n+1];
    for(int i=1;i<=n;i++)
    {
        in>>points[i].x;
        in>>points[i].y;
    }
    in.close();
    lines = new line[n*n];
    for(int i=1;i<=n-1;i++)
        for(int j=i+1;j<=n;j++)
    {
        ++u;
        lines[u].A.x = points[i].x;
        lines[u].A.y = points[i].y;
        lines[u].B.x = points[j].x;
        lines[u].B.y = points[j].y;
    }
    for(int i=1;i<u;i++)
       for(int j=i+1;j<=u;j++)
        if(m_line(lines[i],lines[j]))
       {
            nr++;
       }
       out<<nr<<'\n';
    out.close();
    delete[] points;
    delete[] lines;
    return 0;
}