// only miss the sun when it starts to snow
#include<bits/stdc++.h>
#include "trilib.h"
#define F first
#define S second
#define PB push_back
#define PF push_front
#define sz(s) int((s).size())
#define bit(n,k) (((n)>>(k))&1)
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const int maxn=1e5+10,mod=1e9+7;
const ll inf=1e18;
/*
int get_n(){ //
return 4;
}
int give_answer(int x){
cout<<"ANS "<<x<<endl;
exit(0);
}
bool is_clockwise(int a,int b,int c){
cout<<a<<" "<<b<<" "<<c<<endl;
bool x; cin>>x;
return x;
}*/
deque<int> solve(deque<int>v){
/* cout<<"GONNA SOLVE ";
for(int x:v)
cout<<x<<" ";
cout<<endl;
*/
if(sz(v)<=2) return v;
random_shuffle(v.begin(), v.end());
deque<int> v1, v2;
int A= v.back(), B=v[sz(v)-2];
v.pop_back(), v.pop_back();
for(int i=0; i<sz(v); i++){
if(is_clockwise(A,B,v[i]) == 0) v1.PB(v[i]);
else v2.PB(v[i]);
}
if(v1.empty()){
v2.PB(B);
v2=solve(v2);
while(v2.front() != B)
v2.PF(v2.back()), v2.pop_back();
while(sz(v2)>2 && is_clockwise(v2[ sz(v2)-2 ], v2[sz(v2)-1], A) == 0) v2.pop_back();
v2.PB(A);
v1=v2;
}
else if(v2.empty()){
v1.PB(A);
v1=solve(v1);
while(v1.front() != A)
v1.PF(v1.back()), v1.pop_back();
while(sz(v1)>2 && is_clockwise(v1[ sz(v1)-2 ], v1[ sz(v1)-1 ], B) == 0) v1.pop_back();
v1.PB(B);
}
else{
v1.PB(A), v1.PB(B);
v2.PB(A), v2.PB(B);
v1= solve(v1), v2=solve(v2);
// cout<<"ALSKASLA "<<endl;
reverse(v2.begin(), v2.end());
while(v1.front()!=A || v1.back()!=B)
v1.PF(v1.back()), v1.pop_back();
while(v2.front()!=A || v2.back()!=B)
v2.PF(v2.back()), v2.pop_back();
v2.pop_back();
v1.pop_front();
/*
cout<<"SALAAAA ";
for(int x:v1) cout<<x<<" ";
cout<<endl;
cout<<"SALLAA2 ";
for(int x:v2) cout<<x<<" ";
cout<<endl;
*/
while(true){
if(sz(v1)>1 && is_clockwise(v1[sz(v1)-2], v1[sz(v1)-1], v2.back()) == 0)
v1.pop_back();
else if(sz(v2)>1 && is_clockwise(v1[sz(v1)-1], v2[sz(v2)-1], v2[sz(v2)-2]) == 0)
v2.pop_back();
else
break;
}
while(true){
if(sz(v2)>1 && is_clockwise(v2[1], v2[0], v1[0]) == 0)
v2.pop_front();
else if(sz(v1)>1 && is_clockwise(v2[0], v1[0], v1[1]) == 0)
v1.pop_front();
else
break;
}
reverse(v2.begin(), v2.end());
for(int x:v2)
v1.PB(x);
}
/* cout<<"END "<<" ";
for(int x:v1)
cout<<x<<" ";
cout<<endl;*/
return v1;
}
int main(){
int n=get_n();
srand(time(0));
deque<int> v;
for(int i=1;i<=n;i++)
v.PB(i);
v= solve(v);
give_answer(sz(v));
}
