//package  com.company;


import java.util.Scanner;

public class Main{

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

    }
} import java.util.Scanner; Scanner java.util public class Main{

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

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

    } main {
        Scanner sc=new Scanner(System.in);
        StringBuilder ans=new StringBuilder();
        long n=sc.nextLong();
        while(n>0){
            n--;
            ans.append((char) ((n % 26) + 'a'));
            n/=26;
        }
        System.out.println(ans.reverse().toString());

    } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) StringBuilder ans=new StringBuilder(); ans new StringBuilder() long n=sc.nextLong(); n sc.nextLong() sc.nextLong sc 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().toString()) System.out.println System.out System System.out ans.reverse().toString() ans.reverse().toString ans.reverse() ans.reverse ans String[] args args public class Main{

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

    }
} public class Main{

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

    }
} Main
//package  com.company;


import java.util.Scanner;

public class Main{

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

    }
}