#include<bits/stdc++.h>
#include<iostream>
#include<stdio.h>
#include<string.h>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<stack>
#include<queue>
#include<vector>
#include<map>
#include<cstdlib>
#include<set>
#define PI acos(-1)
#define e 0.01
#define maxn 1000000000
using namespace std;
typedef long long ll;
ll gcd(ll x, ll y)
{
    return x ? gcd(y%x, x) : y;
}
ll lcm(ll x, ll y)
{
    return x * y / gcd(x, y);
}
int main ()
{
    ll n;
    while(~scanf("%lld",&n))
    {
        ll ans=lcm(2,n);
        printf("%lld\n",ans);
    }
    return 0;
}