#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double ld;
#define all(v) v.begin(),v.end()
#define nl "\n"
#define FIO \
    ios_base::sync_with_stdio(false);\
    cin.tie(NULL);\
    cout.tie(NULL);

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

int32_t main()
{
 FIO
    ll t=1;
    // cin>>t;
    for(ll i=1;i<=t;i++)
    {
        // cout<<"Case "<<i<<": ";
        solve();
    }
}