#include<bits/stdc++.h>
using namespace std;
#define INIT  ios_base :: sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define mp make_pair
#define pb push_back
#define ft first
#define sc second
#define ll long long
#define pii pair<int, int>
#define count_bits __builtin_popcount
#define int ll


ifstream f1("trapez.in"); ofstream f2("trapez.out");
#define cin f1
#define cout f2


int t, n, x[1010], y[1010];
vector<pii> pr;



int32_t main(){
INIT
cin>>n;
for(int i=1; i<=n; i++){
    cin>>y[i]>>x[i];
}

int cnt=0;

for(int i=1; i<=n; i++){
    for(int j=i+1; j<=n; j++){
        int dx=x[j]-x[i], dy=y[j]-y[i]; int gcd=__gcd(dx, dy); dx/=gcd; dy/=gcd;
        if(dx<0){dx=-dx; dy=-dy;}
        pr.pb(mp(dx, dy));
        }
}
sort(pr.begin(), pr.end());
int f=-1, s=-1;
int cnt0=0;
for(int i=0; i<pr.size(); i++){
   // cout<<pr[i].ft<<" "<<pr[i].sc<<"\n";
    if(pr[i].ft>f){
        cnt0=0;
    }
    if(pr[i].sc!=s){
        cnt0=0;
    }
    s=pr[i].sc; f=pr[i].ft;
    cnt+=cnt0; cnt0++;
}


cout<<cnt;



return 0;
}