#include <cstdio>
#include <algorithm>
#include <vector>

using namespace std;
vector <int> p;
vector <long long> p1;
vector <long long> p2;
long long x[1001],y[1001],n,nr=0,k=0,ct=0,ct1=0,ct2=0;

bool comp(int i, int j){return (p1[i]*p2[j])<(p2[i]*p1[j]);}

int main(){
	
	freopen("trapez.in","r",stdin);
	scanf("%lld",&n);
	
	for (int i=0;i<n;i++){
		scanf("%lld %lld",&x[i],&y[i]);
	}

	fclose(stdin);

	for(int i=0;i<n-1;i++){
		for(int j=i+1;j<n;j++){
			if((x[i]==x[j])||(y[i]==y[j])){
				if(x[i]==x[j])ct1++;
				if(y[i]==y[j])ct2++;
			}else{
				p1.push_back(y[i]-y[j]);
				p2.push_back(x[i]-x[j]);
				p.push_back(p1.size()-1);
			}
		}
	}
	if (ct1!=0)nr+=ct1*(ct1-1)/2;
	if (ct2!=0)nr+=ct2*(ct2-1)/2;

	sort(p.begin(),p.end(), comp);

	int l=p1.size();
	k=p[0];
	ct++;
	for (int i=1;i<l;i++){
		if ((p1[k]*p2[p[i]])!=(p2[k]*p1[p[i]])){
			k=p[i];
			nr+=ct*(ct-1)/2;
			ct=1;
		}else ct++;
	}
	/*for (int i=0;i<l-1;i++){
		for(int j=i+1;j<l;j++){
			if((p1[i]*p2[j])==(p2[i]*p1[j]))nr++;
		}
	}*/

	freopen("trapez.out","w",stdout);
	printf("%lld",nr);
	fclose(stdout);
	
	return 0;
}