#include <cstdio>
#include <algorithm>
#include <vector>
#include <cstdlib>
#include <cmath>

using namespace std;

const double INF=1e9;
const double eps=1e-9;

class Point{
    private:
        short x,y;
    public:
        Point(){
            x=0; y=0;
        }
        Point(short a, short b){
            x=a; y=b;
        }
        void set(short a, short b){
            x=a; y=b;
        }
        friend bool operator < (const Point &other1, const Point &other2){
            if(other1.x<other1.y)
                return true;
            if(other1.x==other1.y)
                return other1.y < other1.x;
            return false;
        }
        bool operator == (const Point &other){
            return (x==other.x) && (y==other.y);
        }
        double panta(const Point &other){
            if(fabs(x-other.x)<eps)
                return INF;
            return 1.0*(y-other.y)/(x-other.x);
        }
};

long total=0;
short n;
short x,y;
double ans;
vector <Point> v;
vector <double> f;

int main()
{
    long i,j;
    vector <double>::iterator it;
    Point neww;
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    scanf("%hd",&n);
    for(i=1; i<=n; ++i){
        scanf("%hd %hd",&x,&y);
        neww.set(x,y);
        v.push_back(neww);
    }
    for(i=0; i<n; ++i)
        for(j=i+1; j<n; ++j){
           ans=v[i].panta(v[j]);
           f.push_back(ans);
        }
    sort(f.begin(),f.end());
    ans=f[0];
    long k=1;
    for(it=f.begin()+1; it!= f.end(); ++it){
        if(ans==*it)
            ++k;
        else{
            total+=(k*(k-1)/2);
            k=1;
            ans=*it;
        }
    }
    total+=(k*(k-1)/2);
    printf("%ld",total);
    return 0;
}