#include <fstream>
#include<algorithm>
#include<ctime>
#include<cstdlib>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
bool k=0;
long i,j,n,nr=1,nr2=0;
float a[1001],b[1001],v[500501];
int main()
{f>>n;
 for(i=1;i<=n;i++)
    f>>a[i]>>b[i];
 for(i=1;i<n;i++)
    for(j=i+1;j<=n;j++)
      if(a[j]-a[i]==0)
        {if(k)
            nr2++;
         k=1;
        }
      else
        {v[nr]=(b[j]-b[i])*1.0000/(a[j]-a[i]);nr++;}
 std::sort(v+1,v+nr,greater<float>());
 for(i=1;i<nr-1;i++)
   if(v[i]==v[i+1])
     nr2++;
 g<<nr2;
 f.close();g.close();
 return 0;
}