import java.util.Scanner;

class Main {

  static final char[] ALPHA = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
  static final long BASE = 26;
  public static void main(String[] args) {
      Scanner s = new Scanner(System.in);
      long n = s.nextLong();
      String name = "";
      if (n == 1) {
          System.out.println("a");
              return;
          }
          while (n != 0) {
              long rem = (n-1) % BASE;
              n = (n-1)/BASE;
              name = ALPHA[(int) (rem)] + name;
          }
          System.out.println(name);
  }
} import java.util.Scanner; Scanner java.util class Main {

  static final char[] ALPHA = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
  static final long BASE = 26;
  public static void main(String[] args) {
      Scanner s = new Scanner(System.in);
      long n = s.nextLong();
      String name = "";
      if (n == 1) {
          System.out.println("a");
              return;
          }
          while (n != 0) {
              long rem = (n-1) % BASE;
              n = (n-1)/BASE;
              name = ALPHA[(int) (rem)] + name;
          }
          System.out.println(name);
  }
} Main static final char[] ALPHA = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'}; ALPHA {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'} 'a' 'b' 'c' 'd' 'e' 'f' 'g' 'h' 'i' 'j' 'k' 'l' 'm' 'n' 'o' 'p' 'q' 'r' 's' 't' 'u' 'v' 'w' 'x' 'y' 'z' static final long BASE = 26; BASE 26 public static void main(String[] args) {
      Scanner s = new Scanner(System.in);
      long n = s.nextLong();
      String name = "";
      if (n == 1) {
          System.out.println("a");
              return;
          }
          while (n != 0) {
              long rem = (n-1) % BASE;
              n = (n-1)/BASE;
              name = ALPHA[(int) (rem)] + name;
          }
          System.out.println(name);
  } main {
      Scanner s = new Scanner(System.in);
      long n = s.nextLong();
      String name = "";
      if (n == 1) {
          System.out.println("a");
              return;
          }
          while (n != 0) {
              long rem = (n-1) % BASE;
              n = (n-1)/BASE;
              name = ALPHA[(int) (rem)] + name;
          }
          System.out.println(name);
  } Scanner s = new Scanner(System.in); s new Scanner(System.in) long n = s.nextLong(); n s.nextLong() s.nextLong s String name = ""; name "" if (n == 1) {
          System.out.println("a");
              return;
          } n == 1 n 1 {
          System.out.println("a");
              return;
          } System.out.println("a") System.out.println System.out System System.out "a" return; while (n != 0) {
              long rem = (n-1) % BASE;
              n = (n-1)/BASE;
              name = ALPHA[(int) (rem)] + name;
          } n != 0 n 0 {
              long rem = (n-1) % BASE;
              n = (n-1)/BASE;
              name = ALPHA[(int) (rem)] + name;
          } long rem = (n-1) % BASE; rem (n-1) % BASE (n-1) n 1 BASE n = (n-1)/BASE n (n-1)/BASE (n-1) n 1 BASE name = ALPHA[(int) (rem)] + name name ALPHA[(int) (rem)] + name ALPHA[(int) (rem)] ALPHA (int) (rem) name System.out.println(name) System.out.println System.out System System.out name String[] args args
import java.util.Scanner;

class Main {

  static final char[] ALPHA = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
  static final long BASE = 26;
  public static void main(String[] args) {
      Scanner s = new Scanner(System.in);
      long n = s.nextLong();
      String name = "";
      if (n == 1) {
          System.out.println("a");
              return;
          }
          while (n != 0) {
              long rem = (n-1) % BASE;
              n = (n-1)/BASE;
              name = ALPHA[(int) (rem)] + name;
          }
          System.out.println(name);
  }
}
