import java.util.Scanner;

public class Main { 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long N = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    for (; N > 0; N = (N - 1) / 26)
        sb.append((char) ((N - 1) % 26 + 'a'));
    System.out.println(sb.reverse().toString());
  }
}     import java.util.Scanner; Scanner java.util public class Main { 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long N = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    for (; N > 0; N = (N - 1) / 26)
        sb.append((char) ((N - 1) % 26 + 'a'));
    System.out.println(sb.reverse().toString());
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long N = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    for (; N > 0; N = (N - 1) / 26)
        sb.append((char) ((N - 1) % 26 + 'a'));
    System.out.println(sb.reverse().toString());
  } main {
    Scanner sc = new Scanner(System.in);
    long N = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    for (; N > 0; N = (N - 1) / 26)
        sb.append((char) ((N - 1) % 26 + 'a'));
    System.out.println(sb.reverse().toString());
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long N = sc.nextLong(); N sc.nextLong() sc.nextLong sc StringBuilder sb = new StringBuilder(); sb new StringBuilder() for (; N > 0; N = (N - 1) / 26)
        sb.append((char) ((N - 1) % 26 + 'a')); ; N > 0 N 0 N = (N - 1) / 26 N = (N - 1) / 26 N (N - 1) / 26 (N - 1) N 1 26 sb.append((char) ((N - 1) % 26 + 'a')); sb.append((char) ((N - 1) % 26 + 'a')) sb.append sb (char) ((N - 1) % 26 + 'a') (N - 1) % 26 (N - 1) N 1 26 'a' System.out.println(sb.reverse().toString()) System.out.println System.out System System.out sb.reverse().toString() sb.reverse().toString sb.reverse() sb.reverse sb String[] args args public class Main { 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long N = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    for (; N > 0; N = (N - 1) / 26)
        sb.append((char) ((N - 1) % 26 + 'a'));
    System.out.println(sb.reverse().toString());
  }
} public class Main { 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long N = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    for (; N > 0; N = (N - 1) / 26)
        sb.append((char) ((N - 1) % 26 + 'a'));
    System.out.println(sb.reverse().toString());
  }
} Main
import java.util.Scanner;

public class Main { 
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long N = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    for (; N > 0; N = (N - 1) / 26)
        sb.append((char) ((N - 1) % 26 + 'a'));
    System.out.println(sb.reverse().toString());
  }
}    