#include<cstdio>
#include<algorithm>
using namespace std;
int main()
{
    freopen("trapez.in","r",stdin);freopen("trapez.out","w",stdout);
    int x[1001],y[1001];float v[500505];int n,s=0,i,j,k=0;
    scanf("%d",&n);
    for(i=1;i<=n;++i)
    {
        scanf("%d%d",&x[i],&y[i]);
        for(j=i-1;j>=1;--j)
            v[++k]=(float)(x[i]-x[j])/(y[i]-y[j]);
    }
    sort(v+1,v+k+1);
    j=0;
    for(i=2;i<=k;++i)
        if(v[i]==v[i-1])
            ++j;
        else
            ++j,s+=j*(j-1)/2,j=0;
    ++j,s+=j*(j-1)/2;
    printf("%d",s);
}