import static java.lang.Long.parseLong;

import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = parseLong(sc.next()) - 1;
    StringBuilder sb = new StringBuilder();
    while (n >= 26) {
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      n--;
    }
    sb.insert(0, (char) ('a' + n));
    System.out.println(sb);
  }
} import static java.lang.Long.parseLong; import static java.lang.Long.parseLong; import static java.lang.Long.parseLong; import java.util.Scanner; Scanner java.util public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = parseLong(sc.next()) - 1;
    StringBuilder sb = new StringBuilder();
    while (n >= 26) {
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      n--;
    }
    sb.insert(0, (char) ('a' + n));
    System.out.println(sb);
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = parseLong(sc.next()) - 1;
    StringBuilder sb = new StringBuilder();
    while (n >= 26) {
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      n--;
    }
    sb.insert(0, (char) ('a' + n));
    System.out.println(sb);
  } main {
    Scanner sc = new Scanner(System.in);
    long n = parseLong(sc.next()) - 1;
    StringBuilder sb = new StringBuilder();
    while (n >= 26) {
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      n--;
    }
    sb.insert(0, (char) ('a' + n));
    System.out.println(sb);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = parseLong(sc.next()) - 1; n parseLong(sc.next()) - 1 parseLong(sc.next()) parseLong sc.next() sc.next sc 1 StringBuilder sb = new StringBuilder(); sb new StringBuilder() while (n >= 26) {
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      n--;
    } n >= 26 n 26 {
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      n--;
    } sb.insert(0, (char) ('a' + n % 26)) sb.insert sb 0 (char) ('a' + n % 26) 'a' n % 26 n 26 n /= 26 n 26 n-- n sb.insert(0, (char) ('a' + n)) sb.insert sb 0 (char) ('a' + n) 'a' n System.out.println(sb) System.out.println System.out System System.out sb String[] args args public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = parseLong(sc.next()) - 1;
    StringBuilder sb = new StringBuilder();
    while (n >= 26) {
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      n--;
    }
    sb.insert(0, (char) ('a' + n));
    System.out.println(sb);
  }
} public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = parseLong(sc.next()) - 1;
    StringBuilder sb = new StringBuilder();
    while (n >= 26) {
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      n--;
    }
    sb.insert(0, (char) ('a' + n));
    System.out.println(sb);
  }
} Main
import static java.lang.Long.parseLong;

import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = parseLong(sc.next()) - 1;
    StringBuilder sb = new StringBuilder();
    while (n >= 26) {
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      n--;
    }
    sb.insert(0, (char) ('a' + n));
    System.out.println(sb);
  }
}