#include <stdio.h>
#define abs(x)(x<0 ? x* -1 : x) 
#define FOR(i,s,d) for(i=(s);i<=(d);++i)
long n,x[1001],y[10001],q=0,c,d,i,j;
long double v[499505];
long double paralel(long,long,long,long);
int main()
{
    freopen ("trapez.in","r",stdin);
    freopen ("trapez.out","w",stdout);
    scanf("%ld",&n);
    FOR (i,1,n){
        scanf("%ld %ld",&x[i],&y[i]);
        }
    FOR (i,1,n-1)
        FOR (j,i+1,n){
            v[++q]=paralel(x[i],x[j],y[i],y[j]);
            }
    FOR (i,1,(n-1)*n/2-1)
        FOR (j,i+1,(n-1)*n/2)
            if(v[i]==v[j])c++;
        printf("%ld\n",c);
    /*FOR (i,1,2*n)
        printf("%0.6lf\n",v[i]);    */
    return 0;
}
long double paralel(long x1,long x2,long y1,long y2)
{
    long double m;
    if(x2-x1!=0)m=(long double)(y2-y1)/(x2-x1);
    else m=-6969;
    return m;
}