// Enjoy your stay. Code by evima

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

using ld = long double;
using ll = long long;
using lll = __int128;
using vl = vector<ll>;
using LOOPVAR_TYPE = ll;

#define all(x) (x).begin(), (x).end()
#define sq(x) ((x) * (x))
#define sz(x) ll((x).size())
#define GET_MACRO(_1, _2, _3, NAME, ...) NAME
#define rep1(i, n) rep2(i, 0, n)
#define rep2(i, a, b) for(LOOPVAR_TYPE i = LOOPVAR_TYPE(a); i < LOOPVAR_TYPE(b); i++)
#define rep(...) GET_MACRO(__VA_ARGS__, rep2, rep1)(__VA_ARGS__)

#define eb emplace_back
#define fir first
#define sec second
#define mp make_pair
#define mt make_tuple

const ld EPS = 1e-9;
const ld PI = 3.14159265358979323846L;
const ll INF = 1070000000LL;
const ll MOD = 998244353LL;// 1000000007LL;

void fast_io() { cin.tie(NULL); ios_base::sync_with_stdio(false); }
ll lin() { ll x; cin >> x; return x; }
string input() { string s; cin >> s; return s; }
vl vin(int n) { vector<ll> v(n); rep(i, n) cin >> v[i]; return v; }
template<typename T> bool chmin(T& a, const T& b) { return (b < a) ? (a = b, true) : false; }
template<typename T> bool chmax(T& a, const T& b) { return (a < b) ? (a = b, true) : false; }
template<typename T> map<T, ll> freq(const vector<T>& v){ map<T, ll> ret; for(T x: v) ++ret[x]; return ret; }
template<typename T> vector<T> reversed(vector<T> v) { reverse(all(v)); return v; }
template<typename T> vector<T> sorted(vector<T> v) { sort(all(v)); return v; }
template<typename T> vector<T> sub(const vector<T>& v, int from, int to) { vector<T> ret; copy(&v[from], &v[to], back_inserter(ret)); return ret; }
template<typename T> string str(const T& x, int prec = 20) { stringstream ss; ss << setprecision(prec) << x; return ss.str(); }
template<typename Tuple, size_t... I> array<int, sizeof...(I)> str_tuple_impl(stringstream& ss, Tuple&& t, index_sequence<I...>){ return {{ (void( ss << str(get<I>(t)) << " " ), 0)... }}; }
template<typename Tuple> string str_tuple(Tuple&& t){ stringstream ss; str_tuple_impl(ss, forward<Tuple>(t), make_index_sequence<tuple_size<decay_t<Tuple>>::value>{}); string s = ss.str(); if(s.size() > 0) s.pop_back(); return s; }
template<typename T, typename U> string str(const pair<T, U>& p) { return str_tuple(p); }
template<typename... T> string str(const tuple<T...>& t) { return str_tuple(t); }
template<typename T> string str(const vector<T>& v, int prec = 20) { stringstream ss; ss << setprecision(prec); rep(i, sz(v)) ss << v[i] << (i < sz(v) - 1 ? " " : ""); return ss.str(); }
template<typename T> void print1(T&& x, const string& end) { cout << str(x) << end; }
void print() { print1("", "\n"); }
template<typename T, typename... U> void print(T&& head, U&&... tail) { print1(head, " "); print(forward<U>(tail)...); }
template<typename T> void eprint1(T&& x, const string& end) { cerr << str(x) << end; }
void eprint() { eprint1("", "\n"); }
template<typename T, typename... U> void eprint(T&& head, U&&... tail) { eprint1(head, " "); eprint(forward<U>(tail)...); }
template<typename... T> void quit(T&&... x) { print(forward<T>(x)...); exit(0); }
template<typename T, typename U> void yn(bool cnd, T&& yes = "Yes", U&& no = "No") { if(cnd) print(yes); else print(no); }
void zip(vl& v) { vl w = v; sort(all(w)); int n = unique(all(w)) - w.begin(); for(ll& x: v) x = lower_bound(&w[0], &w[n], x) - &w[0]; }
vl zipped(vl v) { zip(v); return v; }
map<ll, ll> zipmap(vl v) { map<ll, ll> ret; sort(all(v)); v.erase(unique(all(v)), v.end()); rep(i, sz(v)) ret[v[i]] = i; return ret; }



void solveOne(){
    ll N = lin();
    print(N + (N % 2 == 0));
}

int main(){
    fast_io();
    
    int num_tc = 1;
    // cin >> num_tc;
    
    
    
    rep(tc, 1, num_tc + 1){
        // cout << "Case #" << tc << ": " ;// << endl;
        solveOne();
    }
}