import java.util.Scanner;

public class Main {

  public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();

    String[] list = new String[26];
    char tmp = 'a';
    for (int i = 0; i < 26; i++) {
      list[i] = String.valueOf(tmp++);
    }

    String ans = "";
    while (n > 0) {
      n--;
      int mod = (int) (n % 26);
      ans += list[mod];
      n /= 26;
    }

    StringBuffer str = new StringBuffer(ans);
    String s = str.reverse().toString();
    System.out.println(s);
  }
}
/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