import java.math.BigInteger;
import java.util.*;

public class Main {

    public static void main(String[] args) {
	// write your code here
        Scanner sc = new Scanner(System.in);
        BigInteger inu = new BigInteger(sc.next());
        BigInteger t = new BigInteger("26");

        StringBuilder sb = new StringBuilder();
        while (inu.compareTo(BigInteger.ZERO) > 0) {
            inu = inu.subtract(BigInteger.ONE);
            BigInteger[] big = inu.divideAndRemainder(t);
            inu = big[0];
            char c = (char)(big[1].intValue() + 'a');
            sb.insert(0, c);
        }

        System.out.println(sb.toString());
    }
} import java.math.BigInteger; BigInteger java.math import java.util.*; util.* java public class Main {

    public static void main(String[] args) {
	// write your code here
        Scanner sc = new Scanner(System.in);
        BigInteger inu = new BigInteger(sc.next());
        BigInteger t = new BigInteger("26");

        StringBuilder sb = new StringBuilder();
        while (inu.compareTo(BigInteger.ZERO) > 0) {
            inu = inu.subtract(BigInteger.ONE);
            BigInteger[] big = inu.divideAndRemainder(t);
            inu = big[0];
            char c = (char)(big[1].intValue() + 'a');
            sb.insert(0, c);
        }

        System.out.println(sb.toString());
    }
} Main public static void main(String[] args) {
	// write your code here
        Scanner sc = new Scanner(System.in);
        BigInteger inu = new BigInteger(sc.next());
        BigInteger t = new BigInteger("26");

        StringBuilder sb = new StringBuilder();
        while (inu.compareTo(BigInteger.ZERO) > 0) {
            inu = inu.subtract(BigInteger.ONE);
            BigInteger[] big = inu.divideAndRemainder(t);
            inu = big[0];
            char c = (char)(big[1].intValue() + 'a');
            sb.insert(0, c);
        }

        System.out.println(sb.toString());
    } main {
	// write your code here
        Scanner sc = new Scanner(System.in);
        BigInteger inu = new BigInteger(sc.next());
        BigInteger t = new BigInteger("26");

        StringBuilder sb = new StringBuilder();
        while (inu.compareTo(BigInteger.ZERO) > 0) {
            inu = inu.subtract(BigInteger.ONE);
            BigInteger[] big = inu.divideAndRemainder(t);
            inu = big[0];
            char c = (char)(big[1].intValue() + 'a');
            sb.insert(0, c);
        }

        System.out.println(sb.toString());
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) BigInteger inu = new BigInteger(sc.next()); inu new BigInteger(sc.next()) BigInteger t = new BigInteger("26"); t new BigInteger("26") StringBuilder sb = new StringBuilder(); sb new StringBuilder() while (inu.compareTo(BigInteger.ZERO) > 0) {
            inu = inu.subtract(BigInteger.ONE);
            BigInteger[] big = inu.divideAndRemainder(t);
            inu = big[0];
            char c = (char)(big[1].intValue() + 'a');
            sb.insert(0, c);
        } inu.compareTo(BigInteger.ZERO) > 0 inu.compareTo(BigInteger.ZERO) inu.compareTo inu BigInteger.ZERO BigInteger BigInteger.ZERO 0 {
            inu = inu.subtract(BigInteger.ONE);
            BigInteger[] big = inu.divideAndRemainder(t);
            inu = big[0];
            char c = (char)(big[1].intValue() + 'a');
            sb.insert(0, c);
        } inu = inu.subtract(BigInteger.ONE) inu inu.subtract(BigInteger.ONE) inu.subtract inu BigInteger.ONE BigInteger BigInteger.ONE BigInteger[] big = inu.divideAndRemainder(t); big inu.divideAndRemainder(t) inu.divideAndRemainder inu t inu = big[0] inu big[0] big 0 char c = (char)(big[1].intValue() + 'a'); c (char)(big[1].intValue() + 'a') big[1].intValue() big[1].intValue big[1] big 1 'a' sb.insert(0, c) sb.insert sb 0 c System.out.println(sb.toString()) System.out.println System.out System System.out sb.toString() sb.toString sb String[] args args public class Main {

    public static void main(String[] args) {
	// write your code here
        Scanner sc = new Scanner(System.in);
        BigInteger inu = new BigInteger(sc.next());
        BigInteger t = new BigInteger("26");

        StringBuilder sb = new StringBuilder();
        while (inu.compareTo(BigInteger.ZERO) > 0) {
            inu = inu.subtract(BigInteger.ONE);
            BigInteger[] big = inu.divideAndRemainder(t);
            inu = big[0];
            char c = (char)(big[1].intValue() + 'a');
            sb.insert(0, c);
        }

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

    public static void main(String[] args) {
	// write your code here
        Scanner sc = new Scanner(System.in);
        BigInteger inu = new BigInteger(sc.next());
        BigInteger t = new BigInteger("26");

        StringBuilder sb = new StringBuilder();
        while (inu.compareTo(BigInteger.ZERO) > 0) {
            inu = inu.subtract(BigInteger.ONE);
            BigInteger[] big = inu.divideAndRemainder(t);
            inu = big[0];
            char c = (char)(big[1].intValue() + 'a');
            sb.insert(0, c);
        }

        System.out.println(sb.toString());
    }
} Main
import java.math.BigInteger;
import java.util.*;

public class Main {

    public static void main(String[] args) {
	// write your code here
        Scanner sc = new Scanner(System.in);
        BigInteger inu = new BigInteger(sc.next());
        BigInteger t = new BigInteger("26");

        StringBuilder sb = new StringBuilder();
        while (inu.compareTo(BigInteger.ZERO) > 0) {
            inu = inu.subtract(BigInteger.ONE);
            BigInteger[] big = inu.divideAndRemainder(t);
            inu = big[0];
            char c = (char)(big[1].intValue() + 'a');
            sb.insert(0, c);
        }

        System.out.println(sb.toString());
    }
}
