import java.lang.*;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        String str = scan.next();

        long num = Long.parseLong(str);
        num--;

        ArrayList<Long> list = new ArrayList<>();

        while (true) {
            list.add(0, num % 26);
            if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            }
        }

        for (long i : list) {
            System.out.print((char)(i + 'a'));
        }
        System.out.println();
    }
} import java.lang.*; lang.* java import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        String str = scan.next();

        long num = Long.parseLong(str);
        num--;

        ArrayList<Long> list = new ArrayList<>();

        while (true) {
            list.add(0, num % 26);
            if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            }
        }

        for (long i : list) {
            System.out.print((char)(i + 'a'));
        }
        System.out.println();
    }
} Main public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        String str = scan.next();

        long num = Long.parseLong(str);
        num--;

        ArrayList<Long> list = new ArrayList<>();

        while (true) {
            list.add(0, num % 26);
            if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            }
        }

        for (long i : list) {
            System.out.print((char)(i + 'a'));
        }
        System.out.println();
    } main {
        Scanner scan = new Scanner(System.in);

        String str = scan.next();

        long num = Long.parseLong(str);
        num--;

        ArrayList<Long> list = new ArrayList<>();

        while (true) {
            list.add(0, num % 26);
            if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            }
        }

        for (long i : list) {
            System.out.print((char)(i + 'a'));
        }
        System.out.println();
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) String str = scan.next(); str scan.next() scan.next scan long num = Long.parseLong(str); num Long.parseLong(str) Long.parseLong Long str num-- num ArrayList<Long> list = new ArrayList<>(); list new ArrayList<>() while (true) {
            list.add(0, num % 26);
            if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            }
        } true {
            list.add(0, num % 26);
            if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            }
        } list.add(0, num % 26) list.add list 0 num % 26 num 26 if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            } num / 26 == 0 num / 26 num 26 0 break; {
                num /= 26;
                num--;
            } num /= 26 num 26 num-- num for (long i : list) {
            System.out.print((char)(i + 'a'));
        } long i list {
            System.out.print((char)(i + 'a'));
        } {
            System.out.print((char)(i + 'a'));
        } System.out.print((char)(i + 'a')) System.out.print System.out System System.out (char)(i + 'a') i 'a' System.out.println() System.out.println System.out System System.out String[] args args public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        String str = scan.next();

        long num = Long.parseLong(str);
        num--;

        ArrayList<Long> list = new ArrayList<>();

        while (true) {
            list.add(0, num % 26);
            if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            }
        }

        for (long i : list) {
            System.out.print((char)(i + 'a'));
        }
        System.out.println();
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        String str = scan.next();

        long num = Long.parseLong(str);
        num--;

        ArrayList<Long> list = new ArrayList<>();

        while (true) {
            list.add(0, num % 26);
            if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            }
        }

        for (long i : list) {
            System.out.print((char)(i + 'a'));
        }
        System.out.println();
    }
} Main
import java.lang.*;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        String str = scan.next();

        long num = Long.parseLong(str);
        num--;

        ArrayList<Long> list = new ArrayList<>();

        while (true) {
            list.add(0, num % 26);
            if (num / 26 == 0) break;
            else {
                num /= 26;
                num--;
            }
        }

        for (long i : list) {
            System.out.print((char)(i + 'a'));
        }
        System.out.println();
    }
}
