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