object Main extends App {


  val n = scala.io.StdIn.readLine().toLong

  def solve(): String = {
    var arr = Array.empty[Long]

    var tmpN = n
    while(tmpN >= 1) {
      arr = tmpN / 26L +: arr
      tmpN /= 26
    }

    val numAndAlphabetMap: Map[Int, String] = (1 to 26).zip(('a' to 'z').map(_.toString)).toMap.updated(0, "")

    arr.foldLeft("") { (acc, num) =>
      acc + numAndAlphabetMap((num % 26).toInt)
    } + numAndAlphabetMap((n % 26).toInt)
  }

  println(solve())

}
