#include <fstream>
#include <algorithm>

using namespace std;

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

int n,z=1;
int x[1005],y[1005];
float panta[1000005];

void b_panta()
{
    for(int i=1; i<n; i++)
        for(int j=i+1; j<=n ; j++)
        {
            if(x[j]!=x[i])
                panta[z]=((float)y[j]-y[i])/((float)x[j]-x[i]);
            if(x[j]==x[i])
                panta[z]=2000000001;
            z++;
        }
}

int main()
{
    int nr=0;
    in>>n;
    for(int i=1; i<=n; i++)
    {
        in>> x[i] >> y[i];
    }
    b_panta();
    sort(panta+1,panta+z);
    int i=1;
    while(i<z)
    {
        if(panta[i]==panta[i+1])
        {
            nr++;
        }
        i++;
    }
    out<< nr;
    return 0;
}