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

int x[1005],y[1005];
double p[1000005];
    
int main(){
    ifstream fin("trapez.in");
    ofstream fout("trapez.out");
    int N,i,j,nrpair=0,r=0,pp=0;
    
    fin>>N;
    
    for(i=1;i<=N;++i) fin>>x[i]>>y[i]; 
      
    for(i=1;i<N;++i)
      for(j=i+1;j<=N;++j)
       if(x[j]-x[i]==0)p[++pp]=0x3f3f3f3f;
          else p[++pp]=double(y[j]-y[i])/(x[j]-x[i]);
            
    sort(p+1,p+pp+1); 
    
    nrpair=1;
    for(i=1;i<pp;++i)
      if(p[i]==p[i+1])++nrpair;
        else {                         
            r+=((nrpair-1)*nrpair)/2; 
            nrpair=1;
            }           
                   
    fout<<r;    
 return 0;   
}