import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();
        num--;

        String result = "";
        String alp = "abcdefghijklmnopqrstuvwxyz";


        while (true) {
            long syou = num / alp.length();
            long mod = num % alp.length();
            
            String tmp = alp.substring((int)mod, (int)mod + 1);

            result = tmp + result;

            num = syou - 1;
            if (syou == 0) {
                break;
            }
        }

        System.out.println(result);
    }
} import java.util.*; util.* java public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();
        num--;

        String result = "";
        String alp = "abcdefghijklmnopqrstuvwxyz";


        while (true) {
            long syou = num / alp.length();
            long mod = num % alp.length();
            
            String tmp = alp.substring((int)mod, (int)mod + 1);

            result = tmp + result;

            num = syou - 1;
            if (syou == 0) {
                break;
            }
        }

        System.out.println(result);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();
        num--;

        String result = "";
        String alp = "abcdefghijklmnopqrstuvwxyz";


        while (true) {
            long syou = num / alp.length();
            long mod = num % alp.length();
            
            String tmp = alp.substring((int)mod, (int)mod + 1);

            result = tmp + result;

            num = syou - 1;
            if (syou == 0) {
                break;
            }
        }

        System.out.println(result);
    } main {
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();
        num--;

        String result = "";
        String alp = "abcdefghijklmnopqrstuvwxyz";


        while (true) {
            long syou = num / alp.length();
            long mod = num % alp.length();
            
            String tmp = alp.substring((int)mod, (int)mod + 1);

            result = tmp + result;

            num = syou - 1;
            if (syou == 0) {
                break;
            }
        }

        System.out.println(result);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long num = sc.nextLong(); num sc.nextLong() sc.nextLong sc num-- num String result = ""; result "" String alp = "abcdefghijklmnopqrstuvwxyz"; alp "abcdefghijklmnopqrstuvwxyz" while (true) {
            long syou = num / alp.length();
            long mod = num % alp.length();
            
            String tmp = alp.substring((int)mod, (int)mod + 1);

            result = tmp + result;

            num = syou - 1;
            if (syou == 0) {
                break;
            }
        } true {
            long syou = num / alp.length();
            long mod = num % alp.length();
            
            String tmp = alp.substring((int)mod, (int)mod + 1);

            result = tmp + result;

            num = syou - 1;
            if (syou == 0) {
                break;
            }
        } long syou = num / alp.length(); syou num / alp.length() num alp.length() alp.length alp long mod = num % alp.length(); mod num % alp.length() num alp.length() alp.length alp String tmp = alp.substring((int)mod, (int)mod + 1); tmp alp.substring((int)mod, (int)mod + 1) alp.substring alp (int)mod (int)mod + 1 (int)mod 1 result = tmp + result result tmp + result tmp result num = syou - 1 num syou - 1 syou 1 if (syou == 0) {
                break;
            } syou == 0 syou 0 {
                break;
            } break; System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();
        num--;

        String result = "";
        String alp = "abcdefghijklmnopqrstuvwxyz";


        while (true) {
            long syou = num / alp.length();
            long mod = num % alp.length();
            
            String tmp = alp.substring((int)mod, (int)mod + 1);

            result = tmp + result;

            num = syou - 1;
            if (syou == 0) {
                break;
            }
        }

        System.out.println(result);
    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();
        num--;

        String result = "";
        String alp = "abcdefghijklmnopqrstuvwxyz";


        while (true) {
            long syou = num / alp.length();
            long mod = num % alp.length();
            
            String tmp = alp.substring((int)mod, (int)mod + 1);

            result = tmp + result;

            num = syou - 1;
            if (syou == 0) {
                break;
            }
        }

        System.out.println(result);
    }
} Main
import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();
        num--;

        String result = "";
        String alp = "abcdefghijklmnopqrstuvwxyz";


        while (true) {
            long syou = num / alp.length();
            long mod = num % alp.length();
            
            String tmp = alp.substring((int)mod, (int)mod + 1);

            result = tmp + result;

            num = syou - 1;
            if (syou == 0) {
                break;
            }
        }

        System.out.println(result);
    }
}
