#include <iostream>
#include <algorithm>
#include <stdio.h>
#include <climits>

using namespace std;
int N;

struct point{
    int x;
    int y;
};

point P[1000];

double pante[1000000];


void citire(){
    cin >> N;
    for(int i=0; i<N; i++)
        cin >> P[i].x >> P[i].y;
}

double calc_panta(point point1, point point2){
    return ((double)point1.y - point2.y)/(double)((double)point1.x - point2.x);
}

int combinari(int n, int k){
    if(k == 0)
        return 1;
    if(k>n)
        return 0;
    return combinari(n-1, k) + combinari(n-1, k-1);

}

int calc(int k){
    double eps = 0.0000001;
    int cnt = 0;
    int rez = 0;
    for(int i=0; i<k-1; i++){
        if((fabs(pante[i] - pante[i+1])) < eps){
            cnt++;
        }
        else{
            if(cnt == 1)
                rez++;
            else
                if(cnt>1)
                    rez+= combinari(cnt, 2);
        cnt = 0;
        }
    }
    return rez;
}

int main(){
    int rez = 0;
    freopen("trapez.in", "r", stdin);
    freopen("trapez.out", "w", stdout);

    citire();

    int k = 0;
    for(int i=0; i<N-1; i++){
        for(int j=i+1; j<N; j++){
            if(P[i].x == P[j].x )
                pante[k] = INT_MAX;
            else
               pante[k] = calc_panta(P[i], P[j]);
            k++;
        }

    }

    sort(pante, pante+k);

     cout << calc(k);

    return 0;
}