#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
long long n;
int main()
{
    while(~scanf("%lld",&n))
    {
        if(n%2==0)
            printf("%lld\n",n);
        else
        {
            printf("%lld\n",2*n);
        }
    }
    return 0;
}
