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

  val chars = "zabcdefghijklmnopqrstuvwxy"
  
  def num2basenumber(long: Long, base: Int): String = {
    var str = ""
    var temp = long
    while (temp > 0) {
      if (temp % base == 0) {
        str = "z" + str
        temp = 0
      } else {
        val r = temp % base
        str = chars(r.toInt)+str
        temp = temp / base
      }
    }
    str
  }

  val result = num2basenumber(n, 26)
  println(result)
}