#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define srt(v) sort(v.begin(), v.end())
#define rsrt(v) sort(v.rbegin(), v.rend())
#define pb push_back

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

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    //int t; cin >> t;
    //while(t--){
        solve();
    //}
}