#include <bits/stdc++.h>
using namespace std;
namespace atcoder{};using namespace atcoder;

using ull = uint64_t;
using ll = int64_t;
using vi = vector<int>;
using vll = vector<ll>;
using vs = vector<string>;
using ld = long double;
using P = pair<ll,ll>;
using G = vector<vector<int>>;

#ifdef MYDEBUG
#pragma once

#define LO(...) fprintf(stderr, __VA_ARGS__)
#define debug(x) cerr << "\033[33m(line:" << __LINE__ << ") " << #x << ": " << x << "\033[m" << endl

template<class C> string join(const C& c){stringstream ss; for(auto it=c.begin(); it!=c.end();it++){ss << *it;if(it!=c.end())ss<<", ";}return ss.str();}
template<class C> ostream &operator<<(ostream &os, const vector<C>& c){for(auto it=c.begin(); it!=c.end();it++){os << *it;if(it!=c.end())os<<", ";}return os;}
#else
#define LO(...) (void)0
#define debug(x) (void)0
#endif

#define reps(i,a,n) for(ll i##_len = (ll)(n), i = (a); i < i##_len; ++i)
#define rep(i,n) reps(i,0,(n))
#define rrep(i,n) reps(i,1,(n)+1)
#define repd(i,n) for(ll i=(n)-1;i>=0;i--)
#define rrepd(i,n) for(ll i=(n);i>=1;i--)

#define inp(i) ll i; cin >> i;
#define inps(s) string s; cin >> s;
#define inpp(p) cin >> (p).first >> (p).second
#define inpv(v,N) vll v(N);rep(i,N)cin>>v[i];
#define inpg(g,N,M) g.resize(N);rep(i,M){inp(a);inp(b);a--,b--;g[a].push_back(b);g[b].push_back(a);}
#define all(v) begin(v),end(v)
#define YES cout<<"YES\n"
#define NO cout<<"NO\n"
#define yes cout<<"yes\n"
#define no cout<<"no\n"
#define Yes cout<<"Yes\n"
#define No cout<<"No\n"
void YESNO(bool b){cout<<(b?"YES\n":"NO\n");} void yesno(bool b){cout<<(b?"yes\n":"no\n");} void YesNo(bool b){cout<<(b?"Yes\n":"No\n");}

#define SP cout << " "
#define ENDL cout << "\n"
#define ou(i) cout << (i)
#define ous(i) cout << (i) << " "
#define oul(i) cout << (i) << "\n"
#define setfp() cout << fixed << setprecision(16)

template<typename C> void ouv(const C &v){for(auto &&e:v){cout << e;if(&e != &v.back()) cout << ' ';}cout << "\n";}
template<typename C> void ouvadd(const C &v){for(auto &&e:v){cout << e+1;if(&e != &v.back()) cout << ' ';}cout << "\n";}

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

inline ll lg(ll __n) { return sizeof(ll) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }

int dx[8]={1,0,-1,0,1,-1,-1,1};
int dy[8]={0,1,0,-1,1,1,-1,-1};

constexpr ll INF = 1e18;

int main(){
    inp(N);
    oul(N*2-1);

    return 0;
}