import scala.math._
import scala.collection.mutable.ListBuffer

object Main {
  //rt.gc()??§??¬??????????????¬?????????????????????
  //val rt = Runtime.getRuntime()
  val sc = new java.util.Scanner(System.in)
  def main(args: Array[String]) {
    while(sc.hasNext) {
      val n = sc.nextInt
      val ans = n%39 match {
        case 0 => 39
        case m => m
      }
      println(f"3C${ans}%02d")
    }
  }
}