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

using namespace std;
int N;
vector<pair<int,int> > Pct;
vector<pair< pair<int,int>, pair<int,int> > > dr;

#define A first
#define B second
#define C first
#define D second
#define x first
#define y second

void read()
{
    scanf("%d",&N);
    int x,y;
    for(int i = 1; i <= N; ++i)
    {
        scanf("%d%d",&x,&y);
        Pct.push_back(make_pair(x,y));
    }
}

class cmp{
public:
    bool operator()(const pair< pair<int,int>, pair<int,int> > &S1,
                    const pair< pair<int,int>, pair<int,int> > &S2) const
                {
                    return (1LL*S1.B.y - 1LL*S1.A.y)*(1LL*S2.D.x - 1LL*S2.C.x) < (1LL*S2.D.y - 1LL*S2.C.y)*(1LL*S1.B.x - 1LL*S1.A.x);
                }
};

bool egal( pair< pair<int,int>, pair<int,int> > S1,
           pair< pair<int,int>, pair<int,int> > S2)
{
    return (1LL*S1.B.y - 1LL*S1.A.y)*(1LL*S2.D.x - 1LL*S2.C.x) == (1LL*S2.D.y - 1LL*S2.C.y)*(1LL*S1.B.x - 1LL*S1.A.x);
}

void solve()
{
    for(int i = 0; i < N; ++i)
        for(int j = 0; j < i; ++j)
            dr.push_back(make_pair(Pct[i],Pct[j]));
    sort(dr.begin(),dr.end(),cmp());

    int crt = 0,sol = 0;
    for(int i = 1; i < dr.size(); ++i)
        if(egal(dr[i],dr[i-1]))
        {
            ++crt;
            sol += crt;
        }
        else
            crt = 0;
    printf("%d\n",sol);
}

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

    read();
    solve();

    return 0;
}