#include <stdio.h>
#include <vector>
#include <map>
using namespace std;

int modul(int a){return a>0?a:(-1)*a;}

int cmmdc(int a,int b){return b==0?a:cmmdc(b,a%b);}

class Dreapta{
	public : int y,x;
	public: Dreapta(int x1,int y1,int x2,int y2){
				if(x1>x2){
					int aux=x1;x1=x2;x2=aux;
					aux=y1;y1=y2;y2=aux;
				}
				y=y2-y1;
				x=x2-x1;
				int aux=cmmdc(modul(x),modul(y));
				x/=aux;
				y/=aux;
			}
	public: bool operator<(const Dreapta& other)const{if(x<other.x) return true;if(x==other.x) return y<other.y;return false;}
	public: bool operator>(const Dreapta& other)const{if(x>other.x) return true;if(x==other.x) return y>other.y;return false;}
};

int main(){
	freopen("trapez.in","r",stdin);
	freopen("trapez.out","w",stdout);
	int n,x,y;
	vector<pair<int,int> > points;
	scanf("%d",&n);
	for(int i=0;i<n;i++){
		scanf("%d %d",&x,&y);
		points.push_back(pair<int,int>(x,y));
	}

	map<Dreapta,int> drM;

	for(int i=0;i<n-2;i++)
		for(int j=i+1;j<n;j++){
			drM[Dreapta(points[i].first,points[i].second,points[j].first,points[j].second)]++;
		}
	int nr=0;
	for(map<Dreapta,int>::iterator it = drM.begin(); it!=drM.end();it++){
		nr+=(it->second*(it->second-1))/2;
	}
	printf("%d",nr);
	return 0;
}