#include <iostream>
#include <cstdio>
#include <algorithm>

using namespace std;

const int NMax = 1005;
const int inf = 0x3f3f3f3f;
int N;
double pante[NMax*NMax];
int top;

struct Punct
{
    int x, y;
}v[NMax];



void Read()
{
    scanf("%d", &N);

    for(int i=1; i<=N; ++i)
        scanf("%d %d", &v[i].x, &v[i].y);
}

void Solve()
{
    for(int i=1; i<N; ++i)
        for(int j=i+1; j<=N; ++j)
    {
        if(v[i].x == v[j].x)
        {
            pante[++top] = (double)inf;
        }

        else
            pante[++top] = (double)(v[j].y-v[i].y)/(v[j].x-v[i].x);
    }
}

long long sum = 0;

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

    Read();
    Solve();
    sort(pante+1, pante+top+1);

    int nr = 1;
    for(int i=2; i<=top; ++i)
        if(pante[i] == pante[i-1])
            ++nr;
        else
            {sum += (nr*(nr-1));
            nr=1;
            }

    printf("%lld", sum/2);
    return 0;
}