#include<stdio.h>
#include<algorithm>
using namespace std;
struct pct{int x,y;};
bool comp(pct a,pct b){
    if(a.y*b.x<a.x*b.y)
        return true;
    else
        return false;
}
int max1(int a,int b){
    if(a>b)
        return a;
    return b;
}
int min1(int a,int b){
    if(a<b)
        return a;
    return b;
}
pct v[1005],vv[1000*1000+5];
int main(){
freopen("trapez.in","r",stdin);
freopen("trapez.out","w",stdout);
    int n,i,j,sol=1,l,nr=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++,sol++){
        vv[sol].x=v[i].x-v[j].x;
        vv[sol].y=v[i].y-v[j].y;
    }
sol--;
sort(vv+1,vv+sol+1,comp);
for(i=1,l=1;i<=sol-1;i++)
    if(vv[i].y*vv[i+1].x==vv[i].x*vv[i+1].y)
        l++;
    else{
        nr+=l*(l-1)/2;
        l=1;
    }
nr+=l*(l-1)/2;
printf("%d",nr);
return 0;
}