#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <vector>

using namespace std;

// BEGIN NO SAD
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define trav(a, x) for(auto& a : x)
#define all(x) x.begin(), x.end()
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
typedef vector<int> vi;
#define f first
#define s second
#define derr if(1) cerr

void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
 
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#define debug(x...) cerr << "\e[91m"<<__func__<<":"<<__LINE__<<" [" << #x << "] = ["; _print(x); cerr << "\e[39m" << flush;
// END NO SAD

template<class Fun>
class y_combinator_result {
  Fun fun_;
public:
  template<class T>
  explicit y_combinator_result(T &&fun): fun_(std::forward<T>(fun)) {}

  template<class ...Args>
  decltype(auto) operator()(Args &&...args) {
    return fun_(std::ref(*this), std::forward<Args>(args)...);
  }
};

template<class Fun>
decltype(auto) y_combinator(Fun &&fun) {
  return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun));
}

template<class T>
bool updmin(T& a, T b) {
  if(b < a) {
    a = b;
    return true;
  }
  return false;
}
template<class T>
bool updmax(T& a, T b) {
  if(b > a) {
    a = b;
    return true;
  }
  return false;
}
typedef int64_t ll;

template<class T>
struct Point {
	typedef Point P;
	T x, y;
	explicit Point(T x=0, T y=0) : x(x), y(y) {}
	bool operator<(P p) const { return tie(x,y) < tie(p.x,p.y); }
	bool operator==(P p) const { return tie(x,y)==tie(p.x,p.y); }
	P operator+(P p) const { return P(x+p.x, y+p.y); }
	P operator-(P p) const { return P(x-p.x, y-p.y); }
	P operator*(T d) const { return P(x*d, y*d); }
	P operator/(T d) const { return P(x/d, y/d); }
	T dot(P p) const { return x*p.x + y*p.y; }
	T cross(P p) const { return x*p.y - y*p.x; }
	T cross(P a, P b) const { return (a-*this).cross(b-*this); }
	T dist2() const { return x*x + y*y; }
	double dist() const { return sqrt((double)dist2()); }
	// angle to x-axis in interval [-pi, pi]
	double angle() const { return atan2(y, x); }
	P unit() const { return *this/dist(); } // makes dist()=1
	P perp() const { return P(-y, x); } // rotates +90 degrees
	P normal() const { return perp().unit(); }
	// returns point rotated 'a' radians ccw around the origin
	P rotate(double a) const {
		return P(x*cos(a)-y*sin(a),x*sin(a)+y*cos(a)); }
};
typedef Point<ll> P;
pair<vi, vi> ulHull(const vector<P>& S) {
	vi Q(sz(S)), U, L;
	iota(all(Q), 0);                                                                                                                                                                         
	sort(all(Q), [&S](int a, int b){ return S[a] < S[b]; }); 
	trav(it, Q) {
#define ADDP(C, cmp) while (sz(C) > 1 && S[C[sz(C)-2]].cross(\
	S[it], S[C.back()]) cmp 0) C.pop_back(); C.push_back(it);
		ADDP(U, <=); ADDP(L, >=);
	}   
	return {U, L}; 
}

vi convexHull(const vector<P>& S) {
	vi u, l; tie(u, l) = ulHull(S);
	if (sz(S) <= 1) return u;
	if (S[u[0]] == S[u[1]]) return {0};
	l.insert(l.end(), u.rbegin()+1, u.rend()-1);
	return l;
}

void rsolve() {
  int n;
  cin >> n;
  vector<P> v(n);
  for(auto& x: v) cin >> x.x >> x.y;
  vector<P> hull;
  {
    for(int out: convexHull(v)) hull.pb(v[out]);
  }
  vector<int> hullloc(n, -1);
  for(int i = 0; i < n; i++) {
    for(int j = 0; j < sz(hull); j++) {
      if(v[i] == hull[j]) hullloc[i] = j;
    }
  }
  ll ret = 1;
  vector<pair<P, int>> others(n);
  for(int i = 0; i < n; i++) others[i] = {v[i], hullloc[i]};
  for(int i = 0; i < n; i++) {
    if(hullloc[i] >= 0) continue;
    sort(all(others), [&](auto a, auto b) -> bool {
      if(a.f == v[i]) return false;
      if(b.f == v[i]) return true;
      return (a.f-v[i]).angle() < (b.f-v[i]).angle();
    });
    assert(others.back().f == v[i]);
    for(int j = 0; j < sz(others)-1; j++) {
      if(others[j].s < 0) continue;
      int k = (j+1);
      if(k == sz(others)-1) k = 0;
      if(others[k].s < 0) continue;
      int diff = abs(others[j].s - others[k].s);
      if(diff == 1 || diff == sz(hull)-1) ret++;
    }
  }
  cout << ret << "\n";
}
void solve() {
  rsolve();
}

// what would chika do
// are there edge cases (N=1?)
// are array sizes proper (scaled by proper constant, for example 2* for koosaga tree)
// integer overflow?
// DS reset properly between test cases
// are you doing geometry in floating points
// are you not using modint when you should

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
}