//package com.atcoder.contest171.c;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        BigInteger bi = new BigInteger(fs.next());
        BigInteger twentySix = new BigInteger("26");
        StringBuilder sb = new StringBuilder();
        while(bi.compareTo(BigInteger.ZERO)  != 0 ){
            BigInteger k = bi.divide(twentySix);
            int last = Integer.parseInt(bi.mod(twentySix).toString());
            if(last == 0){
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            }
            else{
                sb.insert(0, (char)('a' + (last-1)));
            }
            bi = k;
        }
        System.out.println(sb.toString());

    }

    static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        String next() {
            while (!st.hasMoreTokens())
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] readArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.math.BigInteger; BigInteger java.math import java.util.StringTokenizer; StringTokenizer java.util public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        BigInteger bi = new BigInteger(fs.next());
        BigInteger twentySix = new BigInteger("26");
        StringBuilder sb = new StringBuilder();
        while(bi.compareTo(BigInteger.ZERO)  != 0 ){
            BigInteger k = bi.divide(twentySix);
            int last = Integer.parseInt(bi.mod(twentySix).toString());
            if(last == 0){
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            }
            else{
                sb.insert(0, (char)('a' + (last-1)));
            }
            bi = k;
        }
        System.out.println(sb.toString());

    }

    static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        String next() {
            while (!st.hasMoreTokens())
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] readArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }
} Main public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        BigInteger bi = new BigInteger(fs.next());
        BigInteger twentySix = new BigInteger("26");
        StringBuilder sb = new StringBuilder();
        while(bi.compareTo(BigInteger.ZERO)  != 0 ){
            BigInteger k = bi.divide(twentySix);
            int last = Integer.parseInt(bi.mod(twentySix).toString());
            if(last == 0){
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            }
            else{
                sb.insert(0, (char)('a' + (last-1)));
            }
            bi = k;
        }
        System.out.println(sb.toString());

    } main {
        FastScanner fs = new FastScanner();
        BigInteger bi = new BigInteger(fs.next());
        BigInteger twentySix = new BigInteger("26");
        StringBuilder sb = new StringBuilder();
        while(bi.compareTo(BigInteger.ZERO)  != 0 ){
            BigInteger k = bi.divide(twentySix);
            int last = Integer.parseInt(bi.mod(twentySix).toString());
            if(last == 0){
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            }
            else{
                sb.insert(0, (char)('a' + (last-1)));
            }
            bi = k;
        }
        System.out.println(sb.toString());

    } FastScanner fs = new FastScanner(); fs new FastScanner() BigInteger bi = new BigInteger(fs.next()); bi new BigInteger(fs.next()) BigInteger twentySix = new BigInteger("26"); twentySix new BigInteger("26") StringBuilder sb = new StringBuilder(); sb new StringBuilder() while(bi.compareTo(BigInteger.ZERO)  != 0 ){
            BigInteger k = bi.divide(twentySix);
            int last = Integer.parseInt(bi.mod(twentySix).toString());
            if(last == 0){
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            }
            else{
                sb.insert(0, (char)('a' + (last-1)));
            }
            bi = k;
        } bi.compareTo(BigInteger.ZERO)  != 0 bi.compareTo(BigInteger.ZERO) bi.compareTo bi BigInteger.ZERO BigInteger BigInteger.ZERO 0 {
            BigInteger k = bi.divide(twentySix);
            int last = Integer.parseInt(bi.mod(twentySix).toString());
            if(last == 0){
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            }
            else{
                sb.insert(0, (char)('a' + (last-1)));
            }
            bi = k;
        } BigInteger k = bi.divide(twentySix); k bi.divide(twentySix) bi.divide bi twentySix int last = Integer.parseInt(bi.mod(twentySix).toString()); last Integer.parseInt(bi.mod(twentySix).toString()) Integer.parseInt Integer bi.mod(twentySix).toString() bi.mod(twentySix).toString bi.mod(twentySix) bi.mod bi twentySix if(last == 0){
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            }
            else{
                sb.insert(0, (char)('a' + (last-1)));
            } last == 0 last 0 {
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            } k = k.subtract(BigInteger.ONE) k k.subtract(BigInteger.ONE) k.subtract k BigInteger.ONE BigInteger BigInteger.ONE sb.insert(0,'z') sb.insert sb 0 'z' {
                sb.insert(0, (char)('a' + (last-1)));
            } sb.insert(0, (char)('a' + (last-1))) sb.insert sb 0 (char)('a' + (last-1)) 'a' (last-1) last 1 bi = k bi k System.out.println(sb.toString()) System.out.println System.out System System.out sb.toString() sb.toString sb String[] args args static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        String next() {
            while (!st.hasMoreTokens())
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] readArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    } FastScanner BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringTokenizer st = new StringTokenizer(""); st new StringTokenizer("") String next() {
            while (!st.hasMoreTokens())
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        } next {
            while (!st.hasMoreTokens())
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        } while (!st.hasMoreTokens())
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                } !st.hasMoreTokens() st.hasMoreTokens() st.hasMoreTokens st try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                } IOException e {
                    e.printStackTrace();
                } e.printStackTrace() e.printStackTrace e {
                    st = new StringTokenizer(br.readLine());
                } st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt() {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next int[] readArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        } readArray {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        } int[] a = new int[n]; a new int[n] n for (int i = 0; i < n; i++) a[i] = nextInt(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i a[i] = nextInt(); a[i] = nextInt() a[i] a i nextInt() nextInt return a; a int n n long nextLong() {
            return Long.parseLong(next());
        } nextLong {
            return Long.parseLong(next());
        } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        BigInteger bi = new BigInteger(fs.next());
        BigInteger twentySix = new BigInteger("26");
        StringBuilder sb = new StringBuilder();
        while(bi.compareTo(BigInteger.ZERO)  != 0 ){
            BigInteger k = bi.divide(twentySix);
            int last = Integer.parseInt(bi.mod(twentySix).toString());
            if(last == 0){
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            }
            else{
                sb.insert(0, (char)('a' + (last-1)));
            }
            bi = k;
        }
        System.out.println(sb.toString());

    }

    static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        String next() {
            while (!st.hasMoreTokens())
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] readArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }
} public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        BigInteger bi = new BigInteger(fs.next());
        BigInteger twentySix = new BigInteger("26");
        StringBuilder sb = new StringBuilder();
        while(bi.compareTo(BigInteger.ZERO)  != 0 ){
            BigInteger k = bi.divide(twentySix);
            int last = Integer.parseInt(bi.mod(twentySix).toString());
            if(last == 0){
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            }
            else{
                sb.insert(0, (char)('a' + (last-1)));
            }
            bi = k;
        }
        System.out.println(sb.toString());

    }

    static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        String next() {
            while (!st.hasMoreTokens())
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] readArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }
} Main
//package com.atcoder.contest171.c;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        BigInteger bi = new BigInteger(fs.next());
        BigInteger twentySix = new BigInteger("26");
        StringBuilder sb = new StringBuilder();
        while(bi.compareTo(BigInteger.ZERO)  != 0 ){
            BigInteger k = bi.divide(twentySix);
            int last = Integer.parseInt(bi.mod(twentySix).toString());
            if(last == 0){
                k = k.subtract(BigInteger.ONE);
                sb.insert(0,'z');
            }
            else{
                sb.insert(0, (char)('a' + (last-1)));
            }
            bi = k;
        }
        System.out.println(sb.toString());

    }

    static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        String next() {
            while (!st.hasMoreTokens())
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] readArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }
}
