#include <bits/stdc++.h>
#include "trilib.h"
using namespace std;
#define sz(x) ((int)size(x))
#define all(x) begin(x), end(x)
#define trace(x) cout << #x << ": " << (x) << endl;
typedef long long ll;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r) { return (int) ((ll) rnd() % (r - l + 1)) + l; }
const int N = 40000;
const ll infL = 3e18;
int n;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
n = get_n();
multiset<int> st;
for (int s = 0; s < 3; ++s) {
//pseudo Jarvis algorithm
int p0 = s, pi = s;
int k = 0;
do {
++k;
pi = -1;
for (int i = 0; i < n; ++i) {
if (p0 != i && (pi == -1 || is_clockwise(p0 + 1, pi + 1, i + 1))) {
pi = i;
}
}
p0 = pi;
} while (pi != s || k <= n);
if (k > n) {
cout << n - 1;
return 0;
}
st.insert(k);
}
if (st.count(*st.begin()) >= 2) {
cout << *st.begin();
} else {
cout << *st.rbegin();
};
return 0;
}
