import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    long pre_total = 0;
    long total = 0;
    int mojisuu = 0;

    long n = sc.nextLong();
    StringBuilder val = new StringBuilder();


    while(n>0){
      val.append(alpha((int)((n-1)%26)));
      n = (n-1) /26;
    }




      //0x61 = ９７ = a

      System.out.println(val.reverse());
    }








  static char alpha(int n){
      return (char)(n+97);
  }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz