#define wiwihorz
#pragma GCC optimize("Ofast")
#pragma loop-opt(on)
#include <bits/stdc++.h>
#include "trilib.h"
#define rep(i, a, b) for(int i = a; i <= b; i ++)
#define rrep(i, a, b) for(int i = b; i >= a; i--)
#define all(x) x.begin(), x.end()
#define ceil(a, b) ((a + b - 1) / (b))
#define INF 1000000000000000000
#define MOD 1000000007
#define eps (1e-9)
using namespace std;
#define int long long int
#define lld long double
#define pii pair<int, int>
#define random mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count())
#ifdef wiwihorz
#define print(a...) cerr << "Line " << __LINE__ <<": ", kout("[" + string(#a) + "] = ", a)
void kout() {cerr << endl;}
void vprint(auto L, auto R) { while(L < R)cerr << *L << " \n"[next(L) == R], ++L;}
template<class T1, class ... T2> void kout(T1 a, T2 ... e) { cerr << a << " ", kout(e...); }
#else
#define print(...) 0
#define vprint(...) 0
#endif
namespace solver {
vector<int> v[2], hull;
void solve() {
int n = get_n();
v[0].push_back(1);
v[1].push_back(2);
rep(i, 3, n) v[is_clockwise(2, 1, i)].push_back(i);
rep(i, 0, 1) sort(v[i].begin() + 1, v[i].end(),
[](int a, int b) { return is_clockwise(1, b, a);});
rep(tp, 0, 1) {
for(auto i : v[tp]) {
while(hull.size() > 1 && is_clockwise(
hull[hull.size() - 1], i, hull[hull.size() - 2])) hull.pop_back();
hull.push_back(i);
}
}
int ft = 0, bk = hull.size() - 1;
while(true) {
bool done = 1;
while(is_clockwise(hull[bk], hull[ft], hull[bk - 1])) {
done = 0, bk--;
}
while(is_clockwise(hull[ft], hull[ft + 1], hull[bk])) {
done = 0, ft++;
}
if(done) break;
}
give_answer(bk - ft + 1);
return;
}
};
using namespace solver;
signed main() {
ios::sync_with_stdio(false), cin.tie(0);
solve();
return 0;
}
