/*DavitMarg*/
#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <cstring>
#include <map>
#include <set>
#include <queue>
#include <iomanip>
#include <stack>
#include <cassert>
#include <iterator>
#include <bitset>
#include <fstream>
#define death
#ifndef death
#include<trilib.h>
#endif // death
#define mod 1000000007ll
#define LL long long
#define LD long double
#define MP make_pair
#define PB push_back
#define all(v) v.begin(),v.end()
using namespace std;
struct pt
{
LL x, y;
pt(LL X = 0, LL Y = 0)
{
x = X;
y = Y;
}
};
#ifdef death
int get_n()
{
int x;
cin >> x;
return x;
}
vector<pair<LL, LL>> point;
bool is_clockwise(int a, int b, int c)
{
return 0;
}
void give_answer(int x)
{
cout << x << endl;
}
#endif // death
map<pair<int, pair<int, int>>, bool> used, pre;
bool cw(pt a, pt b, pt c) {
return a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y) < 0;
}
bool ccw(pt a, pt b, pt c) {
return a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y) > 0;
}
int ans, n;
vector<pt> p;
int convex_hull(vector<pt> a) {
sort(a.begin(), a.end(), [](pt a, pt b) {
if (a.x == b.x)
return a.x < b.x;
return a.y < b.y;
});
pt p1 = a[0], p2 = a.back();
vector<pt> up, down;
up.push_back(p1);
down.push_back(p1);
for (size_t i = 1; i < a.size(); ++i) {
if (i == a.size() - 1 || cw(p1, a[i], p2)) {
while (up.size() >= 2 && !cw(up[up.size() - 2], up[up.size() - 1], a[i]))
up.pop_back();
up.push_back(a[i]);
}
if (i == a.size() - 1 || ccw(p1, a[i], p2)) {
while (down.size() >= 2 && !ccw(down[down.size() - 2], down[down.size() - 1], a[i]))
down.pop_back();
down.push_back(a[i]);
}
}
a.clear();
for (size_t i = 0; i < up.size(); ++i)
a.push_back(up[i]);
for (size_t i = down.size() - 2; i > 0; --i)
a.push_back(down[i]);
return a.size();
}
int main()
{
n = get_n();
#ifdef death
point.PB(MP(0, 0));
for (int i = 0; i < n; i++)
{
LL x, y;
cin >> x >> y;
p.PB(pt(x, y));
}
#endif // death
ans = convex_hull(p);
give_answer(ans);
return 0;
}
/*
4
5 10
0 0
4 3
10 0
*/
