// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>
#include "trilib.h"
using namespace std;
#define nl '\n'
#define pb push_back
#define sz(x) int(x.size())
template<class T> using V = vector<T>;
using vi = V<int>;
mt19937 rng(1008);
// g++-13 -O2 trilib.cpp A.cpp -std=c++17 -o ./G
int main() {
cin.tie(0)->sync_with_stdio(0);
int N = get_n();
vi L = {1}, R;
for(int i = 2; i < N; i++) {
if (!is_clockwise(1, 2, i + 1)) L.pb(i);
else R.pb(i);
}
sort(begin(L), end(L), [&](int x, int y) {
return is_clockwise(1, x + 1, y + 1);
});
sort(begin(R), end(R), [&](int x, int y) {
return is_clockwise(1, x + 1, y + 1);
});
L.insert(begin(L), 0);
// for(auto& x : L) cout << x << " ";
// cout << endl;
// for(auto& x : R) cout << x << " ";
// cout << endl;
auto fix = [&](vi A) {
vi C;
for(int i = 0; i < sz(A); i++) {
while(sz(C) >= 2 && !is_clockwise(C[sz(C) - 2] + 1, C[sz(C) - 1] + 1, A[i] + 1)) C.pop_back();
C.pb(A[i]);
}
return C;
};
L = fix(L); R = fix(R);
vi C = L; C.insert(end(C), begin(R), end(R));
C = fix(C);
// for(auto& x : C) cout << x << " ";
// cout << endl;
deque<int> D(begin(C), end(C));
while(1) {
bool done = 1;
int x = D.back(); D.pop_back();
if (!is_clockwise(D.back() + 1, x + 1, D.front() + 1)) done = 0;
else D.pb(x);
int y = D.front(); D.pop_front();
if (!is_clockwise(D.back() + 1, y + 1, D.front() + 1)) done = 0;
else D.push_front(y);
if (done) break;
}
// for(auto& x : D) cout << x << " ";
// cout << endl;
give_answer(sz(D));
exit(0-0);
}
