import core.bitop;
import std.algorithm;
import std.ascii;
import std.bigint;
import std.conv;
import std.functional;
import std.format;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.random;
import std.typecons;
 
alias sread = () => readln.chomp();
alias Point2 = Tuple!(long, "y", long, "x");
 
T lread(T = long)()
{
    return readln.chomp.to!T();
}
 
T[] aryread(T = long)()
{
    return readln.split.to!(T[])();
}
 
void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}

void main()
{
    auto a = lread();
    (a%2?a*2:a).writeln();
}