#include<stdio.h>
#include<algorithm>
using namespace std;

typedef struct punct
{
    int x,y;
}punct;

punct v[1002];
double panta[1000002];

int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    int n,i,j,nr=0,l=0,sol=0;
    scanf("%d",&n);
    for(i=1;i<=n;++i)
        scanf("%d%d",&v[i].x,&v[i].y);
    for(i=1;i<n;++i)
        for(j=i+1;j<=n;++j)
            panta[++nr]=double(v[j].y-v[i].y)/(v[j].x-v[i].x);
    sort(panta+1,panta+1+nr);
    ++nr;
    for(i=1;i<=nr;++i)
    {
        if(panta[i]==panta[i-1])
            ++l;
        else
        {
            sol+=l*(l-1)/2;
            l=1;
        }
    }
    printf("%d\n",sol);
    return 0;
}