import java.util.Scanner

import scala.io.StdIn._
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 % 26 +: arr
      tmpN /= 26
    }

    val numAndAlphabetMap: Map[Int, String] = (1 to 25).zip(('a' to 'y').map(_.toString)).toMap.updated(0, "z")

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

  println(solve())

}
