#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define ll long long
#define bug(a) cout<<#a<<" : "<<a<<endl;
void solve(){
    int n; cin>>n;
    if(n % 2 == 0){
        cout<<n<<endl;
        return;
    }else{
        cout<<n-1<<endl;
    }
}
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    // int t; cin>>t;
    // while(t--)
        solve();

    return 0;
}