//SUST_ZadeedBoss_Fanclub
//code_korlei_life_ase
//na_korle_lifeNai

#include<bits/stdc++.h>
using namespace std;
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// template <typename T> using o_set = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
// #define int long long
// #define double long double
// #define all(x) x.begin(), x.end()
// #define rall(x) x.rbegin(), x.rend()
// mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count()); 

void solve ()
{

	int x; cin >>x;
	if (x&1) cout <<x-1 <<"\n";
	else cout <<x <<"\n";

}

signed main()
{

	ios_base::sync_with_stdio(0);
	cin.tie(NULL);

	int TCASE = 1;
	// cin >> TCASE;

	for (int tcase = 1; tcase <= TCASE; tcase++)
	{
		// cout <<"Case #" <<tcase <<": ";
		solve();
	}

}