// https://abc102.contest.atcoder.jp/tasks/abc102_a

function f(n) {
  return n % 2 === 0 ? n : n * 2
}

module.exports = {
  f,
}

function Main(input) {
  const n = parseInt(input.trim(), 10)

  console.log(f(n))
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"))
