/*
    Look at me!
    Look at me!
    The monster inside me has grown this big!
*/

#include<fstream>
#include<iostream>
#include<cstdio>
#include<map>
#include<set>
#define FIT(a,b) for(vector<pair<int,int> >::iterator a=b.begin();a!=b.end();a++)
#define RIT(a,b) for(vector<int>::reverse_iterator a=b.end();a!=b.begin();++a)
#include<stack>
#define ROF(a,b,c) for(int a=b;a>=c;--a)
#include<vector>
#include<algorithm>
#define FOR(a,b,c) for(int a=b;a<=c;++a)
#define REP(a,b) for(register int a=0;a<b;++a)
#include<cstring>
#include<bitset>
#include<cmath>
#include<iomanip>
#define f cin
#define g cout
#include<queue>
#define debug cerr<<"OK";
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define x first
#define y second
#define ll long long
#define ull unsigned long long
#define eps 1.e-9
#define N 700
#define M 500100
using namespace std;
/*int dx[]={0,0,0,1,-1};
int dy[]={0,1,-1,0,0};*/

long long sol;
int n,t;
double dr[N*N];
pair<double,double> v[N];
int main ()
{

    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);


    f>>n;
    FOR(i,1,n)
    {
        f>>v[i].x>>v[i].y;
    }
    FOR(i,1,n)
    FOR(j,i+1,n)
    {
        pair<double,double> a=v[i];
        pair<double,double> b=v[j];
        if(a.x>b.x)
        swap(a,b);
        if(a.x==b.x)
        {
            dr[++t]=1.0/eps;
        }
        else
            dr[++t]=(b.y-a.y)/(b.x-a.x);
    }
    sort(dr+1,dr+t+1);
    FOR(i,1,t)
    {
        int p=i;
        while(dr[i]==dr[i+1])
            ++i;
        sol+=1LL*(i-p+1)*(i-p)/2;
    }
    g<<sol;
    return 0;
}