#include<bits/stdc++.h>
using namespace std;
struct pr{
	int x,y,d;
	bool operator<(const pr&oth)const{return d<oth.d;}
};

vector<int>par;

int find(int x){
	if(par.at(x)==x)return x;
	return par.at(x)=find(par.at(x));
}

bool same(int x,int y){
	return find(x)==find(y);
}

void unite(int x,int y){
	x=find(x),y=find(y);
	if(x==y)return;
	par.at(x)=y;
}

int main(){
	cin.tie(0),ios::sync_with_stdio(false);
	int64_t n; cin>>n;
	cout<<n/2*2+1<<"\n"s;
}