Problem:
Score : 300 points

Problem Statement

1000000000000001 dogs suddenly appeared under the roof of Roger's house, all of which he decided to keep. The dogs had been numbered 1 through 1000000000000001, but he gave them new names, as follows:

the dogs numbered 1,2,\cdots,26 were respectively given the names a, b, ..., z;

the dogs numbered 27,28,29,\cdots,701,702 were respectively given the names aa, ab, ac, ..., zy, zz;

the dogs numbered 703,704,705,\cdots,18277,18278 were respectively given the names aaa, aab, aac, ..., zzy, zzz;

the dogs numbered 18279,18280,18281,\cdots,475253,475254 were respectively given the names aaaa, aaab, aaac, ..., zzzy, zzzz;

the dogs numbered 475255,475256,\cdots were respectively given the names aaaaa, aaaab, ...;

and so on.

To sum it up, the dogs numbered 1, 2, \cdots were respectively given the following names:

a, b, ..., z, aa, ab, ..., az, ba, bb, ..., bz, ..., za, zb, ..., zz, aaa, aab, ..., aaz, aba, abb, ..., abz, ..., zzz, aaaa, ...

Now, Roger asks you:

"What is the name for the dog numbered N?"

Constraints

N is an integer.

1 \leq N \leq 1000000000000001

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer to Roger's question as a string consisting of lowercase English letters.

Sample Input 1

2

Sample Output 1

b

Sample Input 2

27

Sample Output 2

aa

Sample Input 3

123456789

Sample Output 3

jjddja

Solution in Scala (2.13.1) (judge verdict: Accepted)

import java.security.KeyStore.TrustedCertificateEntry
import java.util
import java.util.regex.Pattern
import java.util.{ArrayList, Collections, Comparator, List => JList}

import scala.collection.immutable.TreeMap
import scala.math._
import scala.collection.mutable
import scala.collection.mutable.{ArrayBuffer, ListBuffer}
import scala.util.{Failure, Success, Try}

object Main{
  val LINE_SEPARATOR = "\n"
  def main(args: Array[String]): Unit = {
    if (sys.env.getOrElse("TEST", "")=="1"){
      println(test());
    }else{
      val input=io.Source.stdin.getLines().mkString(LINE_SEPARATOR);
      println(solve(input).trim());
    }
  }

  def init (nRows: Int, nCols: Int, default: Int) = Array.tabulate(nRows,nCols)( (x,y) =>  default)

  def sortIgnoreCase1(list: JList[String]): JList[String] = {
    val r = new ArrayList[String](list)
    Collections.sort(r, new Comparator[String] {
      override def compare(o1: String, o2: String): Int = o1.compareToIgnoreCase(o2)
    })
    r
  }

//  def solve(input: String): String = {
//    val Array(n, q) = input.split(LINE_SEPARATOR).head.split(" ").map(_.toInt)
//    val a = input.split(LINE_SEPARATOR).tail.take(n).map(_.split(" ").head.toInt)
//    val b = input.split(LINE_SEPARATOR).tail.take(n).map(_.split(" ").tail.head.toInt)
//    val c = input.split(LINE_SEPARATOR).drop(n + 1).map(_.split(" ").head.toInt)
//    val d = input.split(LINE_SEPARATOR).drop(n + 1).map(_.split(" ").tail.head.toInt)
//    val k = 2 * pow(10, 5).toInt
//    val INF = pow(10, 9).toInt + 1
//    val pqMap = (0 until k).map(_ => new mutable.TreeMap[Int, Int]).toArray
//    def add(k: Int, ai: Int): Unit = {
//      val count = pqMap(k).getOrElse(ai, 0)
//      pqMap(k) += ai -> (count + 1)
//    }
//    def delete(k: Int, ai: Int): Unit = {
//      val count = pqMap(k).getOrElse(ai, 0)
//      if (count == 1) pqMap(k) -= ai else pqMap(k) += ai -> (count - 1)
//    }
//    val i2k = (0 until n).map{i =>
//      b(i)
//    }.toArray
//    (0 until n).foreach{i =>
//      add(b(i) - 1, a(i))
//    }
//    val maxList = pqMap.map(pq => if (pq.nonEmpty) pq.last._1 else INF)
//
//    (0 until q).map{j =>
//      add(d(j) - 1, a(c(j) - 1))
//      delete(i2k(c(j) - 1) - 1, a(c(j) - 1))
//      maxList(i2k(c(j) - 1) - 1) =
//        if (pqMap(i2k(c(j) - 1) - 1).nonEmpty) pqMap(i2k(c(j) - 1) - 1).last._1 else INF
//      i2k(c(j) - 1) = d(j)
//      maxList(d(j) - 1) = if (pqMap(d(j) - 1).nonEmpty) pqMap(d(j) - 1).last._1 else INF
//      maxList.min
//    }.mkString(LINE_SEPARATOR)
//  }

  def solve(input: String): String = {
    val n = input.toLong
    def f(n: Long): String = {
      var n2 = n
      if (n2 == 0) return ""
      n2 -= 1
      f(n2/26) + (97 + n2%26).toChar
    }

    f(n)
  }

  def divideDigits(num: Long, base: Long = 10L): List[Long] = {
    def proc(num: Long, base: Long, flg: Boolean): List[Long] = {
      var flag = flg
      val quotient = num / base
      val remainder = if (num % base == 0) {
        flag = true
        base
      } else if (flag) {
        flag = false
        val temp = num % base - 1
        if (temp == 0) {
          flag = true
          base
        } else temp
      } else {
        flag = flg
        num % base
      }
      quotient match {
        case 0 =>
          if (flag) {
            List.empty
          } else List(remainder)
        case _ => remainder :: proc(quotient, base, flag)
      }
    }

    proc(num, base, false).reverse//.filterNot(_ == 0)
  }


  def medianCalculator(seq: Seq[Long]): Long = {
    //In order if you are not sure that 'seq' is sorted
    val sortedSeq = seq.sortWith(_ < _)

    if (seq.size % 2 == 1) sortedSeq(sortedSeq.size / 2)
    else {
      val (up, down) = sortedSeq.splitAt(seq.size / 2)
      (up.last + down.head) / 2
    }
  }

  def factorize(x: Long): List[Long] = {
    def foo(x: Long, a: Long = 2, list: List[Long] = Nil): List[Long] = a*a > x match {
      case false if x % a == 0 => foo(x / a, a    , a :: list)
      case false               => foo(x    , a + 1, list)
      case true                => x :: list
    }
    foo(x)
  }

  def divisors(n: Int): Vector[Int] = {
    val halfList = (1 to sqrt(n).toInt).toVector.filter(n % _ == 0).map(_.toInt)
    val reversedList = if (sqrt(n).floor == sqrt(n)) halfList.reverse.tail.map(n/_) else halfList.reverse.map(n/_)
    halfList ++ reversedList
  }

  def gcd(m: Long, n: Long): Long = n match {
    case 0 => m
    case _ => gcd(n, m % n)
  }
  def lcm(a: Long, b: Long): Long = a * b / gcd(a, b)

  val tests=List(
    """2""".stripMargin -> """b
                                                |
                             |
                                   |
                                      |""".stripMargin
    ,
    """27""".stripMargin -> """aa
                             |""".stripMargin,
    """123456789""" -> """jjddja""",
    """1000000000000001""" -> "test",
    """702""" -> """zz""",
    """703""" -> "aaa",
    """26""" -> "z",
    """677""" -> """za""",
    """1353""" -> """aza""",
    """456977""" -> """zzza"""
  )

  def test():String= {
    return tests.map{case (i,o)=>(i.trim(),o.trim())}
      .zipWithIndex.map{
      case ((input,outputExpect),i)=>{
        val output=solve(input).trim();
        s"test${i+1}:"+(if(output==outputExpect){
          "Passed"
        }else{
          s"Failed\nexpect:\n${outputExpect}\noutput:\n${output}"
        })
      }}
      .mkString("\n");
  }



}