import java.util.*;

public class Main {
  public static void main(String[] args) throws Exception {
    Scanner sc = new Scanner(System.in);
    Long N = sc.nextLong();
    
    String name = "";
    
    while(N>0){
      N = N-1;
      String x = String.valueOf(Character.toChars((int)(N%26)+97));
      name = x.concat(name);
      if(N >=26){
        N = (Long)N/26;
      } else {
        break;
      }
    }
    System.out.println(name);
  }
}
/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