#include <bits/stdc++.h>
#include "trilib.h"
using namespace std;
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#define flash ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
#define debug(x) cerr << " - " << #x << ": " << x << endl;
#define debugs(x, y) cerr << " - " << #x << ": " << x << " " << #y << ": " << y << endl;
#define all(x) (x).begin(),(x).end()
#define sz(x) (ll)x.size()
#define ll long long
#define INF 1000000000
#define MOD 1000000007
#define pb push_back
#define ve vector<ll>
#define dos pair<ll,ll>
#define vedos vector<dos>
#define rand mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define EPS 0.000001
struct greateri
{
template<class T>
bool operator()(T const &a, T const &b) const { return a > b; }
};
void setIO(string s) {
ios_base::sync_with_stdio(0); cin.tie(0);
freopen((s+".in").c_str(),"r",stdin);
freopen((s+".out").c_str(),"w",stdout);
}
int k[40001];
map<pair<dos,ll>,bool>g;
bool ask(ll x,ll y,ll z){
if(g.find({{x,y},z})!=g.end())return g[{{x,y},z}];
ll f=is_clockwise(x+1,y+1,z+1);
g[{{x,y},z}]=f;
return f;
}
ll finfirsti(ve k){
for (ll i = 0; i < k.size(); ++i)
{
bool ka=1;
ll cur=i;
ll nex=(i+1)%k.size();
for (ll j = 0; j < k.size(); ++j)
{
if(j!=cur && j!=nex){
ll yo=ask(cur,nex,j);
if(yo){
nex=j;
}
}
}
for (ll j = 0; j < k.size(); ++j)
{
if(j!=cur && j!=nex){
ll yo=ask(cur,nex,j);
if(yo){
ka=0;break;
}
}
}
if(ka)return i;
}
}
ll a;
int compare(const void * va, const void * vi)
{
ll v1=(*(int*)va);
ll v2=(*(int*)vi);
ll o = ask(a, v1, v2);
o=1-o;
o++;
return (o == 2)? -1: 1;
}
ll nextToTop(stack<ll>sa){
sa.pop();
return sa.top();
}
int main()
{
flash;
ll n=get_n();
ve cur,cu,con;
for (ll i = 0; i < n; ++i)
{
cur.pb(i);
}
//debug(1)
a=finfirsti(cur);
//debug(1)
for (ll i = 0; i < n; ++i)
{
if(i!=a)cu.pb(i);
}
for (int i = 0; i < cu.size(); ++i)
{
k[i]=cu[i];
}
if(n==3){
give_answer(3);
}
else{
qsort(k,n-1,sizeof(int),compare);
con.pb(a);
for (int i = 0; i < n-1; ++i)
{
con.pb(k[i]);
}
stack<ll> S;
S.push(con[0]);
S.push(con[1]);
S.push(con[2]);
//debug(con[0])
//debug(con[1])
//debug(con[2])
for (ll i = 3; i < n; i++)
{
//debug(con[i])
//debug(ask(nextToTop(S), S.top(), con[i]))
while (sz(S)>1 && (1-ask(nextToTop(S), S.top(), con[i])+1) != 2)
{
//debug(S.top())
S.pop();
}
S.push(con[i]);
}
give_answer(S.size());
}
return 0;
}
//code the AC sol !
// BS/queue/map
