#include <bits/stdc++.h>
#define int long long
using namespace std;
void solve();
struct pt
{
int x, y;
pt operator + (pt p) { return {x + p.x, y + p.y}; }
pt operator - (pt p) { return {x - p.x, y - p.y}; }
bool operator ==(pt p) { return (x == p.x && y == p.y); }
int cross(pt p) { return x * p.y - y * p.x; }
int cross(pt a, pt b) { return (a - *this).cross(b - *this); }
int dot(pt p) { return x * p.x + y * p.y; }
};
bool cmp_x(pt a, pt b)
{
if (a.x != b.x)
return a.x < b.x;
return a.y < b.y;
}
vector<pt> convex_hull(vector<pt> pts)
{
if (pts.size() <= 1)
return pts;
sort(pts.begin(), pts.end(), cmp_x);
vector<pt> h(pts.size() + 1);
int s = 0, t = 0;
for (int it = 2; it--; s = --t, reverse(pts.begin(), pts.end()))
{
for (auto const &p : pts)
{
while(t >= s + 2 && h[t - 2].cross(h[t - 1], p) <= 0) t--;
h[t++] = p;
}
}
return {h.begin(), h.begin() + t - (t == 2 && h[0] == h[1])};
}//求点集的凸包
int sgn(int x)
{
return (x > 0) - (x < 0);
}
int side_of(pt s, pt e, pt p)
{
return sgn(s.cross(e, p));
}
bool on_segment(pt s, pt e, pt p)
{
return p.cross(s, e) == 0 && (s - p).dot(e - p) <= 0;
}
bool is_hull(vector<pt> &l, pt p, bool strict = true)
{
int a = 1, b = l.size() - 1, r = !strict;
if (l.size() < 3)
return r && on_segment(l[0], l.back(), p);
if (side_of(l[0], l[a], l[b]) > 0) swap(a, b);
if (side_of(l[0], l[a], p) >= r || side_of(l[0], l[b], p) <= -r)
return false;
while(abs(a - b) > 1)
{
int c = (a + b) / 2;
(side_of(l[0], l[c], p) > 0 ? b : a) = c;
}
return sgn(l[a].cross(l[b], p)) < r;
}//判断点是否在凸包内（true在凸包内）
#define pb push_back
const int N = 500010;
const double eps = 1e-8;
inline bool equals(double a, double b)//判断相等
{
return fabs(a - b) < eps;
}
struct Point//点 向量
{
double x, y;
Point() {}
Point(double x, double y) :x(x), y(y) {}
Point operator + (Point& b)
{
return Point(x + b.x, y + b.y);
}
Point operator - (Point& b)
{
return Point(x - b.x, y - b.y);
}
Point operator * (double k)
{
return Point(x * k, y * k);
}
Point operator / (double k)
{
return Point(x / k, y / k);
}
bool operator < (Point b)
{
return equals(x, b.x) ? y < b.y : x < b.x;
}
friend bool operator != (Point a, Point b){
return a.x != b.x || a.y != b.y;
}
};
typedef Point Vector;
inline double get_atan2(Point a, Point b)//求极角
{
Vector v = b - a;
return atan2(v.y, v.x);
}
struct Segment//线段 直线 射线
{
Point p1, p2;//若表示射线则起点为p1
double ang;
Segment() {}
Segment(Point a, Point b) :p1(a), p2(b), ang(get_atan2(p1, p2)) {}
friend operator < (Segment a, Segment b){
if(a.p1 != b.p1){
return a.p1 < b.p1;
}
else return a.p2 < b.p2;
}
};
inline bool cmp_ang(Segment a, Segment b)//极角排序
{
return a.ang < b.ang;
}
signed main(){
cin.sync_with_stdio(0);
cin.tie(0);
int T = 1;
//cin >> T;
while(T--){
solve();
}
return 0;
}
void solve(){
int n;
cin>>n;
vector<pt>v(n);
for(int i=0;i<n;i++) {
cin>>v[i].x>>v[i].y;
}
vector<pt>res=convex_hull(v);//求凸包
// for(auto [x,y]:res){
// cout << x << " " << y << "\n";
// }
int ans = 1;
for(int i=0;i<n;i++) {
if(is_hull(res,v[i])) {//判断点是否在凸包内
vector<Segment> a;
for(auto [x,y]:res){
a.push_back(Segment({v[i].x,v[i].y},{x,y}));
}
vector<Segment> b;
for(int j = 0;j < n;j++){
if(i != j){
b.push_back(Segment({v[i].x,v[i].y}, {v[j].x,v[j].y}));
}
}
map<Segment, int> mp;
int idx = 0;
sort(a.begin(), a.end(), cmp_ang);
sort(b.begin(), b.end(), cmp_ang);
for(auto s:b){
mp[s] = idx++;
}
// cout << i << "\n";
// cout << "a:\n";
// for(auto s:a){
// cout << s.p2.x << " " << s.p2.y << "\n";
// }
// cout << "b:\n";
// for(auto s:b){
// cout << s.p2.x << " " << s.p2.y << "\n";
// }
for(int j = 0;j < a.size();j++){
int z = a.size();
int nj = (j + 1) % z;
if(abs(mp[a[j]] - mp[a[nj]]) == 1){
//cout << i << "\n";
ans++;
}
else if(mp[a[j]] == (int)b.size() - 1 && mp[a[nj]] == 0){
//cout << i << "\n";
ans++;
}
else if(mp[a[j]] == 0 && mp[a[nj]] == (int)b.size() - 1){
//cout << i << "\n";
ans++;
}
}
}
}
cout << ans << "\n";
}