#include<cstdio>
using namespace std;
int n,i,j,h=0,x,xx,y,yy,ct=0;
struct sheldon{int l,c;};
sheldon v[1001],s[1000001];
FILE *in, *out;
int main ()
{
    in=fopen("trapez.in","r");
    out=fopen("trapez.out","w");
    fscanf(in,"%d",&n);
    for(i=1;i<=n;i++)
        fscanf(in,"%d %d",&v[i].l,&v[i].c);
    for(i=1;i<n;i++)
        for(j=i+1;j<=n;j++)
        {
            h++;
            s[h].l=v[j].l-v[i].l;
            s[h].c=v[j].c-v[i].c;
        }
    for(i=1;i<h;i++)
        for(j=i+1;j<=h;j++)
            if(s[i].l*s[j].c == s[i].c*s[j].l)
                ct++;
    fprintf(out,"%d\n",ct);
    return 0;
}