#include <bits/stdc++.h>
using namespace std;
#define LMAX 1005
int x[LMAX],y[LMAX];
double tg[LMAX*LMAX];
int main(){
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    int n,N=0,k=0;
    scanf("%d",&n);
    for(int i=1;i<=n;++i)
        scanf("%d %d",&x[i],&y[i]);
    for(int i=1;i<n;++i)
        for(int j=i+1;j<=n;++j)
            tg[++k]=1.0*(y[i]-y[j])/(x[i]-x[j]);
    sort(tg+1,tg+k+1);
    for(int i=1;i<=k;++i){
        int no=0;
        while(tg[i]==tg[i+1]&&i+1<=k){
            ++no;
            ++i;
        }
        N+=no*(no+1)/2;
    }
    printf("%d",N);
    fclose(stdin);fclose(stdout);
    return 0;
}