#include<bits/stdc++.h>
#define ll long long int
#define endl '\n'
#define print(v) for(auto data : v) cout << data << " "; cout << endl;
using namespace std;
void solve()
{
    int n; cin >> n;
    if(n%2 == 0) cout << n << endl;
    else cout << n-1 << endl;
}
int main ()
{
    ios_base::sync_with_stdio(false); cin.tie(NULL);

    // int t; cin >> t;
    int t = 1;
    while (t--) solve();
    
    return  0;
}