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

#define int long long
#define fo(i,a,n) for(ll i=a;i<n;i++)
#define all(v) v.begin(),v.end()
#define pb push_back
#define fi first
#define sc second
#define endl '\n'
#define gcd(x, y)   (__gcd(x, y))
#define lcm(x, y)   ((x/gcd(x, y))*y)
#define mem(a,b) memset(a, b, sizeof(a))
#define de(x) cerr<<#x<<" :: "<<x<<" "<<endl

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

int32_t main()
{

    //ios_base::sync_with_stdio(false);
    //cin.tie(0), cout.tie(0);

    int t=1;
   // cin>>t;
    while(t--)
    {
        solve();
    }

    return 0;
}