#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int , int> pii;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxn = 2100;
const ll mod = 1e9+7;
const ld PI = acos((ld)-1);
#define pb push_back
#define endl '\n'
#define dokme(x) cout << x , exit(0)
#define migmig ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define ms(x , y) memset(x , y , sizeof x)
ll pw(ll a, ll b, ll md = mod){ll res = 1;while(b){if(b&1){res=(a*res)%md;}a=(a*a)%md;b>>=1;}return(res);}
int n;
struct point{
ll x , y;
}p[maxn];
bool bad[maxn][maxn];
bool ccw(point A,point B,point C){
return (C.y-A.y)*(B.x-A.x) > (B.y-A.y)*(C.x-A.x);
}
bool boom (point A,point B,point C,point D){
return ccw(A,C,D) != ccw(B,C,D) and ccw(A,B,C) != ccw(A,B,D);
}
time_t start , now;
int32_t main(){
migmig;
cin >> n;
for(int i = 1 ; i <= n ; i ++){
cin >> p[i].x >> p[i].y;
}
time(&start);
int ans = 0;
for(int i = 1 ; i <= n ; i ++){
for(int j = i + 1 ; j <= n ; j ++){
time(&now);
if(now - start > 0.98)break;
for(int k = 1 ; k <= n ; k ++){
for(int l = k+1 ; l <= n ; l ++){
if(i^k and i^l and j^k and j^l and boom(p[i] , p[j] , p[k] , p[l])){
bad[k][l] = bad[i][j] = 1;
}
if(bad[i][j])break;
}
if(bad[i][j])break;
}
}
}
for(int i = 1 ; i <= n ; i ++){
for(int j = i + 1 ; j <= n ; j ++){
ans += !bad[i][j];
}
}
cout << ans;
return(0);
}
