import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    String res = func(n);
    System.out.println(res);
  }
  
  public static String func(long n) {
    n--;
    if(n <= 25 && 0 <= n)
      return Character.toString((char)(97 + n));
    String res = func(n/26) + ((char)(97 + (n%26)));
    
    return res;
  }
} import java.util.*; util.* java class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    String res = func(n);
    System.out.println(res);
  }
  
  public static String func(long n) {
    n--;
    if(n <= 25 && 0 <= n)
      return Character.toString((char)(97 + n));
    String res = func(n/26) + ((char)(97 + (n%26)));
    
    return res;
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    String res = func(n);
    System.out.println(res);
  } main {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    String res = func(n);
    System.out.println(res);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = sc.nextLong(); n sc.nextLong() sc.nextLong sc String res = func(n); res func(n) func n System.out.println(res) System.out.println System.out System System.out res String[] args args public static String func(long n) {
    n--;
    if(n <= 25 && 0 <= n)
      return Character.toString((char)(97 + n));
    String res = func(n/26) + ((char)(97 + (n%26)));
    
    return res;
  } func {
    n--;
    if(n <= 25 && 0 <= n)
      return Character.toString((char)(97 + n));
    String res = func(n/26) + ((char)(97 + (n%26)));
    
    return res;
  } n-- n if(n <= 25 && 0 <= n)
      return Character.toString((char)(97 + n)); n <= 25 && 0 <= n n <= 25 n 25 0 <= n 0 n return Character.toString((char)(97 + n)); Character.toString((char)(97 + n)) Character.toString Character (char)(97 + n) 97 n String res = func(n/26) + ((char)(97 + (n%26))); res func(n/26) + ((char)(97 + (n%26))) func(n/26) func n/26 n 26 ((char)(97 + (n%26))) 97 (n%26) n 26 return res; res long n n
import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    String res = func(n);
    System.out.println(res);
  }
  
  public static String func(long n) {
    n--;
    if(n <= 25 && 0 <= n)
      return Character.toString((char)(97 + n));
    String res = func(n/26) + ((char)(97 + (n%26)));
    
    return res;
  }
}
