object Main extends App {
  var n = scala.io.StdIn.readLong

  val chars = "abcdefghijklmnopqrstuvwxyz"
  
  var str = ""
  while (0 < n) {
    val r = n % 26
    str = chars(r.toInt-1) +: str
    n = n / 26
  }

  println(str)
}