import java.io.*;

/**
 * Created by Ayushi on 21 Jun 2020.
 * Problem:
 * Round:
 */

public class Main {
    public static void main(String[] args) throws IOException {
        //StringTokenizer st;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        long n = Long.parseLong(br.readLine());
        br.close();
        long l; //, r;
        l = 0;
        long c;
        int t;
        for (t = 1; t <= 13; t++) {
            c = (long) (l + (Math.pow(26, t)));
            if (n <= c) {
                //r = c;
                break;
            }
            else l = c;
        }
        long d = (n - l) -1;
        long[] a = new long[t];
        for (int i = t-1; i >= 0; i--) {
            a[i] = Math.max((d%26) + 97, 97);
            d = d/26;
        }
        for (int j = 0; j < t; j++) {
            System.out.print((char)a[j]);
            //System.out.println(a[j]);
        }
        System.out.println();
    }
} import java.io.*; io.* java public class Main {
    public static void main(String[] args) throws IOException {
        //StringTokenizer st;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        long n = Long.parseLong(br.readLine());
        br.close();
        long l; //, r;
        l = 0;
        long c;
        int t;
        for (t = 1; t <= 13; t++) {
            c = (long) (l + (Math.pow(26, t)));
            if (n <= c) {
                //r = c;
                break;
            }
            else l = c;
        }
        long d = (n - l) -1;
        long[] a = new long[t];
        for (int i = t-1; i >= 0; i--) {
            a[i] = Math.max((d%26) + 97, 97);
            d = d/26;
        }
        for (int j = 0; j < t; j++) {
            System.out.print((char)a[j]);
            //System.out.println(a[j]);
        }
        System.out.println();
    }
} Main public static void main(String[] args) throws IOException {
        //StringTokenizer st;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        long n = Long.parseLong(br.readLine());
        br.close();
        long l; //, r;
        l = 0;
        long c;
        int t;
        for (t = 1; t <= 13; t++) {
            c = (long) (l + (Math.pow(26, t)));
            if (n <= c) {
                //r = c;
                break;
            }
            else l = c;
        }
        long d = (n - l) -1;
        long[] a = new long[t];
        for (int i = t-1; i >= 0; i--) {
            a[i] = Math.max((d%26) + 97, 97);
            d = d/26;
        }
        for (int j = 0; j < t; j++) {
            System.out.print((char)a[j]);
            //System.out.println(a[j]);
        }
        System.out.println();
    } main {
        //StringTokenizer st;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        long n = Long.parseLong(br.readLine());
        br.close();
        long l; //, r;
        l = 0;
        long c;
        int t;
        for (t = 1; t <= 13; t++) {
            c = (long) (l + (Math.pow(26, t)));
            if (n <= c) {
                //r = c;
                break;
            }
            else l = c;
        }
        long d = (n - l) -1;
        long[] a = new long[t];
        for (int i = t-1; i >= 0; i--) {
            a[i] = Math.max((d%26) + 97, 97);
            d = d/26;
        }
        for (int j = 0; j < t; j++) {
            System.out.print((char)a[j]);
            //System.out.println(a[j]);
        }
        System.out.println();
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) long n = Long.parseLong(br.readLine()); n Long.parseLong(br.readLine()) Long.parseLong Long br.readLine() br.readLine br br.close() br.close br long l; l l = 0 l 0 long c; c int t; t for (t = 1; t <= 13; t++) {
            c = (long) (l + (Math.pow(26, t)));
            if (n <= c) {
                //r = c;
                break;
            }
            else l = c;
        } t = 1; t = 1 t 1 t <= 13 t 13 t++ t++ t {
            c = (long) (l + (Math.pow(26, t)));
            if (n <= c) {
                //r = c;
                break;
            }
            else l = c;
        } {
            c = (long) (l + (Math.pow(26, t)));
            if (n <= c) {
                //r = c;
                break;
            }
            else l = c;
        } c = (long) (l + (Math.pow(26, t))) c (long) (l + (Math.pow(26, t))) l (Math.pow(26, t)) Math.pow Math 26 t if (n <= c) {
                //r = c;
                break;
            }
            else l = c; n <= c n c {
                //r = c;
                break;
            } break; l = c l c long d = (n - l) -1; d (n - l) -1 (n - l) n l 1 long[] a = new long[t]; a new long[t] t for (int i = t-1; i >= 0; i--) {
            a[i] = Math.max((d%26) + 97, 97);
            d = d/26;
        } int i = t-1; int i = t-1; i t-1 t 1 i >= 0 i 0 i-- i-- i {
            a[i] = Math.max((d%26) + 97, 97);
            d = d/26;
        } {
            a[i] = Math.max((d%26) + 97, 97);
            d = d/26;
        } a[i] = Math.max((d%26) + 97, 97) a[i] a i Math.max((d%26) + 97, 97) Math.max Math (d%26) + 97 (d%26) d 26 97 97 d = d/26 d d/26 d 26 for (int j = 0; j < t; j++) {
            System.out.print((char)a[j]);
            //System.out.println(a[j]);
        } int j = 0; int j = 0; j 0 j < t j t j++ j++ j {
            System.out.print((char)a[j]);
            //System.out.println(a[j]);
        } {
            System.out.print((char)a[j]);
            //System.out.println(a[j]);
        } System.out.print((char)a[j]) System.out.print System.out System System.out (char)a[j] a j System.out.println() System.out.println System.out System System.out String[] args args public class Main {
    public static void main(String[] args) throws IOException {
        //StringTokenizer st;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        long n = Long.parseLong(br.readLine());
        br.close();
        long l; //, r;
        l = 0;
        long c;
        int t;
        for (t = 1; t <= 13; t++) {
            c = (long) (l + (Math.pow(26, t)));
            if (n <= c) {
                //r = c;
                break;
            }
            else l = c;
        }
        long d = (n - l) -1;
        long[] a = new long[t];
        for (int i = t-1; i >= 0; i--) {
            a[i] = Math.max((d%26) + 97, 97);
            d = d/26;
        }
        for (int j = 0; j < t; j++) {
            System.out.print((char)a[j]);
            //System.out.println(a[j]);
        }
        System.out.println();
    }
} public class Main {
    public static void main(String[] args) throws IOException {
        //StringTokenizer st;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        long n = Long.parseLong(br.readLine());
        br.close();
        long l; //, r;
        l = 0;
        long c;
        int t;
        for (t = 1; t <= 13; t++) {
            c = (long) (l + (Math.pow(26, t)));
            if (n <= c) {
                //r = c;
                break;
            }
            else l = c;
        }
        long d = (n - l) -1;
        long[] a = new long[t];
        for (int i = t-1; i >= 0; i--) {
            a[i] = Math.max((d%26) + 97, 97);
            d = d/26;
        }
        for (int j = 0; j < t; j++) {
            System.out.print((char)a[j]);
            //System.out.println(a[j]);
        }
        System.out.println();
    }
} Main
import java.io.*;

/**
 * Created by Ayushi on 21 Jun 2020.
 * Problem:
 * Round:
 */

public class Main {
    public static void main(String[] args) throws IOException {
        //StringTokenizer st;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        long n = Long.parseLong(br.readLine());
        br.close();
        long l; //, r;
        l = 0;
        long c;
        int t;
        for (t = 1; t <= 13; t++) {
            c = (long) (l + (Math.pow(26, t)));
            if (n <= c) {
                //r = c;
                break;
            }
            else l = c;
        }
        long d = (n - l) -1;
        long[] a = new long[t];
        for (int i = t-1; i >= 0; i--) {
            a[i] = Math.max((d%26) + 97, 97);
            d = d/26;
        }
        for (int j = 0; j < t; j++) {
            System.out.print((char)a[j]);
            //System.out.println(a[j]);
        }
        System.out.println();
    }
}
