#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
 
#define pb push_back
#define MOD 1000000007
#define vll vector<ll>
#define endl "\n" 
#define all(v) v.begin(), v.end()
#define mem(a,b) memset(a, b, sizeof(a))
#define co(n) cout << n << endl
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#define fr(x, n) for (int i = x; i < n; ++i)
#define fraction(x) cout << fixed << setprecision(x)
#define Baba_Yaga ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
 
const double eps = 1e-9;
const int N = 2e5+123;
 
ll gcd(ll a,ll b) { return __gcd(a,b); }
ll lcm(ll a,ll b) { return (a*b)/__gcd(a,b); }
 
int dx[] = {0, 0, +1, -1, +1, +1, -1, -1};
int dy[] = {+1, -1, 0, 0, +1, -1, +1, -1};
 

void solve()
{
    ll n; cin >> n;
    if(n % 2 == 0) cout << n << endl;
    else cout << n-1 << endl;
}

int main()
{
    Baba_Yaga;
    ll tc = 1; //cin >> tc;
    for(int i=1; i<=tc; i++)
    {
       // cout << "Case " << i << ": ";
        solve();
    }   
}