#include <bits/stdc++.h>
#define MAX 131072
#define MOD 10007
#define INF 2100000000

using namespace std;
const int NMAX = 1005;
const long double eps = 0.00000001;

struct obj{
    int x, y;
};

int N, M;
long long ans;
long double slope[NMAX * NMAX];
obj v[NMAX];

int main(){

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

    scanf("%d", &N);
    for(int i = 1; i <= N; i++)
        scanf("%d%d", &v[i].x, &v[i].y);
    for(int i = 1; i <= N; i++)
        for(int j = i + 1; j <= N; j++)
                slope[++M] = (double)(v[j].y - v[i].y) / (double)(v[j].x - v[i].x);
    sort(slope + 1, slope + M + 1);

    int cnt;
    for(int i = 1; i < M; i++){
        cnt = 1;
        while(slope[i + 1] == slope[i] && i < M){
            cnt++;
            i++;
        }
        ans = ans + 1LL * cnt * (cnt - 1) / 2;
    }
    printf("%lld", ans);

    return 0;
}