import java.util.ArrayList;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        long num = 0;
        int count=0;
        while (num<n){
            count++;
            num+=(long)Math.pow(26,count);
        }
        long instance = n-num+(long)Math.pow(26,count)-1;
        ArrayList<Character> array = new ArrayList<>();
        for (int i=0;i<count;i++){
            int mod = (int) (instance%26);
            array.add((char)mod);
            instance /= 26;
        }
        String s = "";
        for (int i=0;i<array.size();i++){
            s = (char) (array.get(i) + 'a') +s;
        }
        System.out.println(s);
    }
} import java.util.ArrayList; ArrayList java.util 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();
        long num = 0;
        int count=0;
        while (num<n){
            count++;
            num+=(long)Math.pow(26,count);
        }
        long instance = n-num+(long)Math.pow(26,count)-1;
        ArrayList<Character> array = new ArrayList<>();
        for (int i=0;i<count;i++){
            int mod = (int) (instance%26);
            array.add((char)mod);
            instance /= 26;
        }
        String s = "";
        for (int i=0;i<array.size();i++){
            s = (char) (array.get(i) + 'a') +s;
        }
        System.out.println(s);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        long num = 0;
        int count=0;
        while (num<n){
            count++;
            num+=(long)Math.pow(26,count);
        }
        long instance = n-num+(long)Math.pow(26,count)-1;
        ArrayList<Character> array = new ArrayList<>();
        for (int i=0;i<count;i++){
            int mod = (int) (instance%26);
            array.add((char)mod);
            instance /= 26;
        }
        String s = "";
        for (int i=0;i<array.size();i++){
            s = (char) (array.get(i) + 'a') +s;
        }
        System.out.println(s);
    } main {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        long num = 0;
        int count=0;
        while (num<n){
            count++;
            num+=(long)Math.pow(26,count);
        }
        long instance = n-num+(long)Math.pow(26,count)-1;
        ArrayList<Character> array = new ArrayList<>();
        for (int i=0;i<count;i++){
            int mod = (int) (instance%26);
            array.add((char)mod);
            instance /= 26;
        }
        String s = "";
        for (int i=0;i<array.size();i++){
            s = (char) (array.get(i) + 'a') +s;
        }
        System.out.println(s);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long n = sc.nextLong(); n sc.nextLong() sc.nextLong sc long num = 0; num 0 int count=0; count 0 while (num<n){
            count++;
            num+=(long)Math.pow(26,count);
        } num<n num n {
            count++;
            num+=(long)Math.pow(26,count);
        } count++ count num+=(long)Math.pow(26,count) num (long)Math.pow(26,count) Math.pow Math 26 count long instance = n-num+(long)Math.pow(26,count)-1; instance n-num+(long)Math.pow(26,count)-1 n-num+(long)Math.pow(26,count) n-num n num (long)Math.pow(26,count) Math.pow Math 26 count 1 ArrayList<Character> array = new ArrayList<>(); array new ArrayList<>() for (int i=0;i<count;i++){
            int mod = (int) (instance%26);
            array.add((char)mod);
            instance /= 26;
        } int i=0; int i=0; i 0 i<count i count i++ i++ i {
            int mod = (int) (instance%26);
            array.add((char)mod);
            instance /= 26;
        } {
            int mod = (int) (instance%26);
            array.add((char)mod);
            instance /= 26;
        } int mod = (int) (instance%26); mod (int) (instance%26) instance 26 array.add((char)mod) array.add array (char)mod instance /= 26 instance 26 String s = ""; s "" for (int i=0;i<array.size();i++){
            s = (char) (array.get(i) + 'a') +s;
        } int i=0; int i=0; i 0 i<array.size() i array.size() array.size array i++ i++ i {
            s = (char) (array.get(i) + 'a') +s;
        } {
            s = (char) (array.get(i) + 'a') +s;
        } s = (char) (array.get(i) + 'a') +s s (char) (array.get(i) + 'a') +s (char) (array.get(i) + 'a') array.get(i) array.get array i 'a' s System.out.println(s) System.out.println System.out System System.out s String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        long num = 0;
        int count=0;
        while (num<n){
            count++;
            num+=(long)Math.pow(26,count);
        }
        long instance = n-num+(long)Math.pow(26,count)-1;
        ArrayList<Character> array = new ArrayList<>();
        for (int i=0;i<count;i++){
            int mod = (int) (instance%26);
            array.add((char)mod);
            instance /= 26;
        }
        String s = "";
        for (int i=0;i<array.size();i++){
            s = (char) (array.get(i) + 'a') +s;
        }
        System.out.println(s);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        long num = 0;
        int count=0;
        while (num<n){
            count++;
            num+=(long)Math.pow(26,count);
        }
        long instance = n-num+(long)Math.pow(26,count)-1;
        ArrayList<Character> array = new ArrayList<>();
        for (int i=0;i<count;i++){
            int mod = (int) (instance%26);
            array.add((char)mod);
            instance /= 26;
        }
        String s = "";
        for (int i=0;i<array.size();i++){
            s = (char) (array.get(i) + 'a') +s;
        }
        System.out.println(s);
    }
} Main
import java.util.ArrayList;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        long num = 0;
        int count=0;
        while (num<n){
            count++;
            num+=(long)Math.pow(26,count);
        }
        long instance = n-num+(long)Math.pow(26,count)-1;
        ArrayList<Character> array = new ArrayList<>();
        for (int i=0;i<count;i++){
            int mod = (int) (instance%26);
            array.add((char)mod);
            instance /= 26;
        }
        String s = "";
        for (int i=0;i<array.size();i++){
            s = (char) (array.get(i) + 'a') +s;
        }
        System.out.println(s);
    }
}
