#include <bits/stdc++.h>
using namespace std;
 
 
 
#define ll long long
#define ull unsigned long long
#define ld long double
#define f(i,n) for(int i=0;i<n;i++)
#define pb push_back
#define YES cout<<"YES\n"
#define NO cout<<"NO\n"
#define endl '\n'
#define vll vector<ll>
#define mll map<ll,ll>
#define MOD 1000000007
#define ANS cout<<ans<<endl
#define fastio ios_base::sync_with_stdio(false);cin.tie(0); cout.tie(0);
ll gcd(ll a, ll b) {return __gcd(a,b);}
ll lcm(ll a, ll b) {return a* (b/gcd(a,b));}
const int m=1e9+7;
long long binpow(long long a, long long b) {
	long long res = 1;
	while (b > 0) {
		if (b & 1)
		res = (res * a)%m;
		a = (a * a)%m;
		b >>= 1;
	}
	return res;
}
int main() {
    ios_base::sync_with_stdio(false);cin.tie(0);
    ll n;cin>>n;
    if(n%2)
    	cout<<n-1<<endl;
    else cout<<n<<endl;

    return 0;
}