import java.io.*;
import java.util.*;

public class Main {
    static PrintWriter pw;
    static Scanner sc;
    static int[] dp;
    static ArrayList<Integer>[] adj;
    static boolean[] visit;
    static long ceildiv(long x, long y) { return (x + y - 1) / y; }
    static int mod(long x, int m) { return (int) ((x % m + m) % m); }
    public static long gcd(long x, long y) {return y == 0 ? x : gcd(y, x % y);}
    public static void main(String[] args) throws Exception {
        sc = new Scanner(System.in);
        pw = new PrintWriter(System.out);
        long x=sc.nextLong();
        StringBuilder sb=new StringBuilder();
        while(x>=1){
            x--;
            sb.append((char)('a'+x%26));
            x/=26;
        }
        pw.println(sb.reverse().toString());
        pw.close();
    }
    static void printArr(int[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    }
    static void printArr(long[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    }
    static void printArr(Integer[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i] + " ");
        pw.println();
    }
    static void printArr(char[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i]);
        pw.println();
    }
    static void printArr(ArrayList list) {
        for (int i = 0; i < list.size(); i++)
            pw.print(list.get(i) + " ");
        pw.println();
    }
    static class Scanner {
        StringTokenizer st;
        BufferedReader br;
        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public Scanner(FileReader r) {
            br = new BufferedReader(r);
        }

        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }

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

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

        public String nextLine() throws IOException {
            return br.readLine();
        }

        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        public int[] nextArr(int n) throws IOException {
            int[] arr = new int[n];
            for (int i = 0; i < arr.length; i++)
                arr[i] = nextInt();
            return arr;
        }
        public Integer[] nextsort(int n) throws IOException{
            Integer[] arr=new Integer[n];
            for(int i=0; i<n; i++)
                arr[i]=nextInt();
            return arr;
        }
        public Pair nextPair() throws IOException{
            return new Pair(nextInt(), nextInt());
        }
        public Pair[] nextPairArr(int n) throws IOException{
            Pair[] arr=new Pair[n];
            for(int i=0; i<n; i++)
                arr[i]=new Pair(nextInt(), nextInt());
            return arr;
        }
        public boolean ready() throws IOException {
            return br.ready();
        }
    }
    static class Pair implements Comparable<Pair>{
        long x;
        long y;
        public Pair(long x, long y) {
            this.x=x;
            this.y=y;
        }
        public int hashCode() {
            return (int)(this.x*1000+this.y);
        }
        public int compareTo(Pair p){
            return (int)(this.x-p.x);
        }
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (this.getClass() != obj.getClass()) {
                return false;
            }
            Pair p = (Pair) obj;
            return this.x==p.x && this.y==p.y;
        }
        public boolean equal(Pair p){
            if(this.x==p.x)
                return this.y==p.y;
            if(this.x==p.y)
                return this.y==p.x;
            else
                return false;
        }
        public Pair clone(){
            return new Pair(x, y);
        }
        public String toString(){
            return this.x+" "+this.y;
        }
        public void add(Pair p){
            x+=p.x;
            y+=p.y;
        }
        public Pair multiply(int x){
            return new Pair(x*this.x, x*this.y);
        }
    }
} import java.io.*; io.* java import java.util.*; util.* java public class Main {
    static PrintWriter pw;
    static Scanner sc;
    static int[] dp;
    static ArrayList<Integer>[] adj;
    static boolean[] visit;
    static long ceildiv(long x, long y) { return (x + y - 1) / y; }
    static int mod(long x, int m) { return (int) ((x % m + m) % m); }
    public static long gcd(long x, long y) {return y == 0 ? x : gcd(y, x % y);}
    public static void main(String[] args) throws Exception {
        sc = new Scanner(System.in);
        pw = new PrintWriter(System.out);
        long x=sc.nextLong();
        StringBuilder sb=new StringBuilder();
        while(x>=1){
            x--;
            sb.append((char)('a'+x%26));
            x/=26;
        }
        pw.println(sb.reverse().toString());
        pw.close();
    }
    static void printArr(int[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    }
    static void printArr(long[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    }
    static void printArr(Integer[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i] + " ");
        pw.println();
    }
    static void printArr(char[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i]);
        pw.println();
    }
    static void printArr(ArrayList list) {
        for (int i = 0; i < list.size(); i++)
            pw.print(list.get(i) + " ");
        pw.println();
    }
    static class Scanner {
        StringTokenizer st;
        BufferedReader br;
        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public Scanner(FileReader r) {
            br = new BufferedReader(r);
        }

        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }

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

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

        public String nextLine() throws IOException {
            return br.readLine();
        }

        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        public int[] nextArr(int n) throws IOException {
            int[] arr = new int[n];
            for (int i = 0; i < arr.length; i++)
                arr[i] = nextInt();
            return arr;
        }
        public Integer[] nextsort(int n) throws IOException{
            Integer[] arr=new Integer[n];
            for(int i=0; i<n; i++)
                arr[i]=nextInt();
            return arr;
        }
        public Pair nextPair() throws IOException{
            return new Pair(nextInt(), nextInt());
        }
        public Pair[] nextPairArr(int n) throws IOException{
            Pair[] arr=new Pair[n];
            for(int i=0; i<n; i++)
                arr[i]=new Pair(nextInt(), nextInt());
            return arr;
        }
        public boolean ready() throws IOException {
            return br.ready();
        }
    }
    static class Pair implements Comparable<Pair>{
        long x;
        long y;
        public Pair(long x, long y) {
            this.x=x;
            this.y=y;
        }
        public int hashCode() {
            return (int)(this.x*1000+this.y);
        }
        public int compareTo(Pair p){
            return (int)(this.x-p.x);
        }
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (this.getClass() != obj.getClass()) {
                return false;
            }
            Pair p = (Pair) obj;
            return this.x==p.x && this.y==p.y;
        }
        public boolean equal(Pair p){
            if(this.x==p.x)
                return this.y==p.y;
            if(this.x==p.y)
                return this.y==p.x;
            else
                return false;
        }
        public Pair clone(){
            return new Pair(x, y);
        }
        public String toString(){
            return this.x+" "+this.y;
        }
        public void add(Pair p){
            x+=p.x;
            y+=p.y;
        }
        public Pair multiply(int x){
            return new Pair(x*this.x, x*this.y);
        }
    }
} Main static PrintWriter pw; pw static Scanner sc; sc static int[] dp; dp static ArrayList<Integer>[] adj; adj static boolean[] visit; visit static long ceildiv(long x, long y) { return (x + y - 1) / y; } ceildiv { return (x + y - 1) / y; } return (x + y - 1) / y; (x + y - 1) / y (x + y - 1) x + y x y 1 y long x x long y y static int mod(long x, int m) { return (int) ((x % m + m) % m); } mod { return (int) ((x % m + m) % m); } return (int) ((x % m + m) % m); (int) ((x % m + m) % m) (x % m + m) x % m x m m m long x x int m m public static long gcd(long x, long y) {return y == 0 ? x : gcd(y, x % y);} gcd {return y == 0 ? x : gcd(y, x % y);} return y == 0 ? x : gcd(y, x % y); y == 0 ? x : gcd(y, x % y) y == 0 y 0 x gcd(y, x % y) gcd y x % y x y long x x long y y public static void main(String[] args) throws Exception {
        sc = new Scanner(System.in);
        pw = new PrintWriter(System.out);
        long x=sc.nextLong();
        StringBuilder sb=new StringBuilder();
        while(x>=1){
            x--;
            sb.append((char)('a'+x%26));
            x/=26;
        }
        pw.println(sb.reverse().toString());
        pw.close();
    } main {
        sc = new Scanner(System.in);
        pw = new PrintWriter(System.out);
        long x=sc.nextLong();
        StringBuilder sb=new StringBuilder();
        while(x>=1){
            x--;
            sb.append((char)('a'+x%26));
            x/=26;
        }
        pw.println(sb.reverse().toString());
        pw.close();
    } sc = new Scanner(System.in) sc new Scanner(System.in) pw = new PrintWriter(System.out) pw new PrintWriter(System.out) long x=sc.nextLong(); x sc.nextLong() sc.nextLong sc StringBuilder sb=new StringBuilder(); sb new StringBuilder() while(x>=1){
            x--;
            sb.append((char)('a'+x%26));
            x/=26;
        } x>=1 x 1 {
            x--;
            sb.append((char)('a'+x%26));
            x/=26;
        } x-- x sb.append((char)('a'+x%26)) sb.append sb (char)('a'+x%26) 'a' x%26 x 26 x/=26 x 26 pw.println(sb.reverse().toString()) pw.println pw sb.reverse().toString() sb.reverse().toString sb.reverse() sb.reverse sb pw.close() pw.close pw String[] args args static void printArr(int[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    } printArr {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    } for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " "); int i = 0; int i = 0; i 0 i < arr.length - 1 i arr.length - 1 arr.length arr arr.length 1 i++ i++ i pw.print(arr[i] + " "); pw.print(arr[i] + " ") pw.print pw arr[i] + " " arr[i] arr i " " pw.println(arr[arr.length - 1]) pw.println pw arr[arr.length - 1] arr arr.length - 1 arr.length arr arr.length 1 int[] arr arr static void printArr(long[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    } printArr {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    } for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " "); int i = 0; int i = 0; i 0 i < arr.length - 1 i arr.length - 1 arr.length arr arr.length 1 i++ i++ i pw.print(arr[i] + " "); pw.print(arr[i] + " ") pw.print pw arr[i] + " " arr[i] arr i " " pw.println(arr[arr.length - 1]) pw.println pw arr[arr.length - 1] arr arr.length - 1 arr.length arr arr.length 1 long[] arr arr static void printArr(Integer[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i] + " ");
        pw.println();
    } printArr {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i] + " ");
        pw.println();
    } for (int i = 0; i < arr.length; i++)
            pw.print(arr[i] + " "); int i = 0; int i = 0; i 0 i < arr.length i arr.length arr arr.length i++ i++ i pw.print(arr[i] + " "); pw.print(arr[i] + " ") pw.print pw arr[i] + " " arr[i] arr i " " pw.println() pw.println pw Integer[] arr arr static void printArr(char[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i]);
        pw.println();
    } printArr {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i]);
        pw.println();
    } for (int i = 0; i < arr.length; i++)
            pw.print(arr[i]); int i = 0; int i = 0; i 0 i < arr.length i arr.length arr arr.length i++ i++ i pw.print(arr[i]); pw.print(arr[i]) pw.print pw arr[i] arr i pw.println() pw.println pw char[] arr arr static void printArr(ArrayList list) {
        for (int i = 0; i < list.size(); i++)
            pw.print(list.get(i) + " ");
        pw.println();
    } printArr {
        for (int i = 0; i < list.size(); i++)
            pw.print(list.get(i) + " ");
        pw.println();
    } for (int i = 0; i < list.size(); i++)
            pw.print(list.get(i) + " "); int i = 0; int i = 0; i 0 i < list.size() i list.size() list.size list i++ i++ i pw.print(list.get(i) + " "); pw.print(list.get(i) + " ") pw.print pw list.get(i) + " " list.get(i) list.get list i " " pw.println() pw.println pw ArrayList list list static class Scanner {
        StringTokenizer st;
        BufferedReader br;
        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public Scanner(FileReader r) {
            br = new BufferedReader(r);
        }

        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }

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

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

        public String nextLine() throws IOException {
            return br.readLine();
        }

        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        public int[] nextArr(int n) throws IOException {
            int[] arr = new int[n];
            for (int i = 0; i < arr.length; i++)
                arr[i] = nextInt();
            return arr;
        }
        public Integer[] nextsort(int n) throws IOException{
            Integer[] arr=new Integer[n];
            for(int i=0; i<n; i++)
                arr[i]=nextInt();
            return arr;
        }
        public Pair nextPair() throws IOException{
            return new Pair(nextInt(), nextInt());
        }
        public Pair[] nextPairArr(int n) throws IOException{
            Pair[] arr=new Pair[n];
            for(int i=0; i<n; i++)
                arr[i]=new Pair(nextInt(), nextInt());
            return arr;
        }
        public boolean ready() throws IOException {
            return br.ready();
        }
    } Scanner StringTokenizer st; st BufferedReader br; br public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        } Scanner {
            br = new BufferedReader(new InputStreamReader(s));
        } br = new BufferedReader(new InputStreamReader(s)) br new BufferedReader(new InputStreamReader(s)) InputStream s s public Scanner(FileReader r) {
            br = new BufferedReader(r);
        } Scanner {
            br = new BufferedReader(r);
        } br = new BufferedReader(r) br new BufferedReader(r) FileReader r r public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        } next {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        } while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine()); st == null || !st.hasMoreTokens() st == null st null !st.hasMoreTokens() st.hasMoreTokens() st.hasMoreTokens st st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st public int nextInt() throws IOException {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public long nextLong() throws IOException {
            return Long.parseLong(next());
        } nextLong {
            return Long.parseLong(next());
        } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next public String nextLine() throws IOException {
            return br.readLine();
        } nextLine {
            return br.readLine();
        } return br.readLine(); br.readLine() br.readLine br public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        } nextDouble {
            return Double.parseDouble(next());
        } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next public int[] nextArr(int n) throws IOException {
            int[] arr = new int[n];
            for (int i = 0; i < arr.length; i++)
                arr[i] = nextInt();
            return arr;
        } nextArr {
            int[] arr = new int[n];
            for (int i = 0; i < arr.length; i++)
                arr[i] = nextInt();
            return arr;
        } int[] arr = new int[n]; arr new int[n] n for (int i = 0; i < arr.length; i++)
                arr[i] = nextInt(); int i = 0; int i = 0; i 0 i < arr.length i arr.length arr arr.length i++ i++ i arr[i] = nextInt(); arr[i] = nextInt() arr[i] arr i nextInt() nextInt return arr; arr int n n public Integer[] nextsort(int n) throws IOException{
            Integer[] arr=new Integer[n];
            for(int i=0; i<n; i++)
                arr[i]=nextInt();
            return arr;
        } nextsort {
            Integer[] arr=new Integer[n];
            for(int i=0; i<n; i++)
                arr[i]=nextInt();
            return arr;
        } Integer[] arr=new Integer[n]; arr new Integer[n] n for(int i=0; i<n; i++)
                arr[i]=nextInt(); int i=0; int i=0; i 0 i<n i n i++ i++ i arr[i]=nextInt(); arr[i]=nextInt() arr[i] arr i nextInt() nextInt return arr; arr int n n public Pair nextPair() throws IOException{
            return new Pair(nextInt(), nextInt());
        } nextPair {
            return new Pair(nextInt(), nextInt());
        } return new Pair(nextInt(), nextInt()); new Pair(nextInt(), nextInt()) public Pair[] nextPairArr(int n) throws IOException{
            Pair[] arr=new Pair[n];
            for(int i=0; i<n; i++)
                arr[i]=new Pair(nextInt(), nextInt());
            return arr;
        } nextPairArr {
            Pair[] arr=new Pair[n];
            for(int i=0; i<n; i++)
                arr[i]=new Pair(nextInt(), nextInt());
            return arr;
        } Pair[] arr=new Pair[n]; arr new Pair[n] n for(int i=0; i<n; i++)
                arr[i]=new Pair(nextInt(), nextInt()); int i=0; int i=0; i 0 i<n i n i++ i++ i arr[i]=new Pair(nextInt(), nextInt()); arr[i]=new Pair(nextInt(), nextInt()) arr[i] arr i new Pair(nextInt(), nextInt()) return arr; arr int n n public boolean ready() throws IOException {
            return br.ready();
        } ready {
            return br.ready();
        } return br.ready(); br.ready() br.ready br static class Pair implements Comparable<Pair>{
        long x;
        long y;
        public Pair(long x, long y) {
            this.x=x;
            this.y=y;
        }
        public int hashCode() {
            return (int)(this.x*1000+this.y);
        }
        public int compareTo(Pair p){
            return (int)(this.x-p.x);
        }
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (this.getClass() != obj.getClass()) {
                return false;
            }
            Pair p = (Pair) obj;
            return this.x==p.x && this.y==p.y;
        }
        public boolean equal(Pair p){
            if(this.x==p.x)
                return this.y==p.y;
            if(this.x==p.y)
                return this.y==p.x;
            else
                return false;
        }
        public Pair clone(){
            return new Pair(x, y);
        }
        public String toString(){
            return this.x+" "+this.y;
        }
        public void add(Pair p){
            x+=p.x;
            y+=p.y;
        }
        public Pair multiply(int x){
            return new Pair(x*this.x, x*this.y);
        }
    } Pair long x; x long y; y public Pair(long x, long y) {
            this.x=x;
            this.y=y;
        } Pair {
            this.x=x;
            this.y=y;
        } this.x=x this.x this this.x x this.y=y this.y this this.y y long x x long y y public int hashCode() {
            return (int)(this.x*1000+this.y);
        } hashCode {
            return (int)(this.x*1000+this.y);
        } return (int)(this.x*1000+this.y); (int)(this.x*1000+this.y) this.x*1000 this.x this this.x 1000 this.y this this.y public int compareTo(Pair p){
            return (int)(this.x-p.x);
        } compareTo {
            return (int)(this.x-p.x);
        } return (int)(this.x-p.x); (int)(this.x-p.x) this.x this this.x p.x p p.x Pair p p public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (this.getClass() != obj.getClass()) {
                return false;
            }
            Pair p = (Pair) obj;
            return this.x==p.x && this.y==p.y;
        } equals {
            if (obj == null) {
                return false;
            }
            if (this.getClass() != obj.getClass()) {
                return false;
            }
            Pair p = (Pair) obj;
            return this.x==p.x && this.y==p.y;
        } if (obj == null) {
                return false;
            } obj == null obj null {
                return false;
            } return false; false if (this.getClass() != obj.getClass()) {
                return false;
            } this.getClass() != obj.getClass() this.getClass() this.getClass this obj.getClass() obj.getClass obj {
                return false;
            } return false; false Pair p = (Pair) obj; p (Pair) obj return this.x==p.x && this.y==p.y; this.x==p.x && this.y==p.y this.x==p.x this.x this this.x p.x p p.x this.y==p.y this.y this this.y p.y p p.y Object obj obj public boolean equal(Pair p){
            if(this.x==p.x)
                return this.y==p.y;
            if(this.x==p.y)
                return this.y==p.x;
            else
                return false;
        } equal {
            if(this.x==p.x)
                return this.y==p.y;
            if(this.x==p.y)
                return this.y==p.x;
            else
                return false;
        } if(this.x==p.x)
                return this.y==p.y; this.x==p.x this.x this this.x p.x p p.x return this.y==p.y; this.y==p.y this.y this this.y p.y p p.y if(this.x==p.y)
                return this.y==p.x;
            else
                return false; this.x==p.y this.x this this.x p.y p p.y return this.y==p.x; this.y==p.x this.y this this.y p.x p p.x return false; false Pair p p public Pair clone(){
            return new Pair(x, y);
        } clone {
            return new Pair(x, y);
        } return new Pair(x, y); new Pair(x, y) public String toString(){
            return this.x+" "+this.y;
        } toString {
            return this.x+" "+this.y;
        } return this.x+" "+this.y; this.x+" "+this.y this.x+" "+this.y this.x this this.x " " this.y this this.y public void add(Pair p){
            x+=p.x;
            y+=p.y;
        } add {
            x+=p.x;
            y+=p.y;
        } x+=p.x x p.x p p.x y+=p.y y p.y p p.y Pair p p public Pair multiply(int x){
            return new Pair(x*this.x, x*this.y);
        } multiply {
            return new Pair(x*this.x, x*this.y);
        } return new Pair(x*this.x, x*this.y); new Pair(x*this.x, x*this.y) int x x Comparable public class Main {
    static PrintWriter pw;
    static Scanner sc;
    static int[] dp;
    static ArrayList<Integer>[] adj;
    static boolean[] visit;
    static long ceildiv(long x, long y) { return (x + y - 1) / y; }
    static int mod(long x, int m) { return (int) ((x % m + m) % m); }
    public static long gcd(long x, long y) {return y == 0 ? x : gcd(y, x % y);}
    public static void main(String[] args) throws Exception {
        sc = new Scanner(System.in);
        pw = new PrintWriter(System.out);
        long x=sc.nextLong();
        StringBuilder sb=new StringBuilder();
        while(x>=1){
            x--;
            sb.append((char)('a'+x%26));
            x/=26;
        }
        pw.println(sb.reverse().toString());
        pw.close();
    }
    static void printArr(int[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    }
    static void printArr(long[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    }
    static void printArr(Integer[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i] + " ");
        pw.println();
    }
    static void printArr(char[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i]);
        pw.println();
    }
    static void printArr(ArrayList list) {
        for (int i = 0; i < list.size(); i++)
            pw.print(list.get(i) + " ");
        pw.println();
    }
    static class Scanner {
        StringTokenizer st;
        BufferedReader br;
        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public Scanner(FileReader r) {
            br = new BufferedReader(r);
        }

        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }

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

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

        public String nextLine() throws IOException {
            return br.readLine();
        }

        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        public int[] nextArr(int n) throws IOException {
            int[] arr = new int[n];
            for (int i = 0; i < arr.length; i++)
                arr[i] = nextInt();
            return arr;
        }
        public Integer[] nextsort(int n) throws IOException{
            Integer[] arr=new Integer[n];
            for(int i=0; i<n; i++)
                arr[i]=nextInt();
            return arr;
        }
        public Pair nextPair() throws IOException{
            return new Pair(nextInt(), nextInt());
        }
        public Pair[] nextPairArr(int n) throws IOException{
            Pair[] arr=new Pair[n];
            for(int i=0; i<n; i++)
                arr[i]=new Pair(nextInt(), nextInt());
            return arr;
        }
        public boolean ready() throws IOException {
            return br.ready();
        }
    }
    static class Pair implements Comparable<Pair>{
        long x;
        long y;
        public Pair(long x, long y) {
            this.x=x;
            this.y=y;
        }
        public int hashCode() {
            return (int)(this.x*1000+this.y);
        }
        public int compareTo(Pair p){
            return (int)(this.x-p.x);
        }
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (this.getClass() != obj.getClass()) {
                return false;
            }
            Pair p = (Pair) obj;
            return this.x==p.x && this.y==p.y;
        }
        public boolean equal(Pair p){
            if(this.x==p.x)
                return this.y==p.y;
            if(this.x==p.y)
                return this.y==p.x;
            else
                return false;
        }
        public Pair clone(){
            return new Pair(x, y);
        }
        public String toString(){
            return this.x+" "+this.y;
        }
        public void add(Pair p){
            x+=p.x;
            y+=p.y;
        }
        public Pair multiply(int x){
            return new Pair(x*this.x, x*this.y);
        }
    }
} public class Main {
    static PrintWriter pw;
    static Scanner sc;
    static int[] dp;
    static ArrayList<Integer>[] adj;
    static boolean[] visit;
    static long ceildiv(long x, long y) { return (x + y - 1) / y; }
    static int mod(long x, int m) { return (int) ((x % m + m) % m); }
    public static long gcd(long x, long y) {return y == 0 ? x : gcd(y, x % y);}
    public static void main(String[] args) throws Exception {
        sc = new Scanner(System.in);
        pw = new PrintWriter(System.out);
        long x=sc.nextLong();
        StringBuilder sb=new StringBuilder();
        while(x>=1){
            x--;
            sb.append((char)('a'+x%26));
            x/=26;
        }
        pw.println(sb.reverse().toString());
        pw.close();
    }
    static void printArr(int[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    }
    static void printArr(long[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    }
    static void printArr(Integer[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i] + " ");
        pw.println();
    }
    static void printArr(char[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i]);
        pw.println();
    }
    static void printArr(ArrayList list) {
        for (int i = 0; i < list.size(); i++)
            pw.print(list.get(i) + " ");
        pw.println();
    }
    static class Scanner {
        StringTokenizer st;
        BufferedReader br;
        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public Scanner(FileReader r) {
            br = new BufferedReader(r);
        }

        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }

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

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

        public String nextLine() throws IOException {
            return br.readLine();
        }

        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        public int[] nextArr(int n) throws IOException {
            int[] arr = new int[n];
            for (int i = 0; i < arr.length; i++)
                arr[i] = nextInt();
            return arr;
        }
        public Integer[] nextsort(int n) throws IOException{
            Integer[] arr=new Integer[n];
            for(int i=0; i<n; i++)
                arr[i]=nextInt();
            return arr;
        }
        public Pair nextPair() throws IOException{
            return new Pair(nextInt(), nextInt());
        }
        public Pair[] nextPairArr(int n) throws IOException{
            Pair[] arr=new Pair[n];
            for(int i=0; i<n; i++)
                arr[i]=new Pair(nextInt(), nextInt());
            return arr;
        }
        public boolean ready() throws IOException {
            return br.ready();
        }
    }
    static class Pair implements Comparable<Pair>{
        long x;
        long y;
        public Pair(long x, long y) {
            this.x=x;
            this.y=y;
        }
        public int hashCode() {
            return (int)(this.x*1000+this.y);
        }
        public int compareTo(Pair p){
            return (int)(this.x-p.x);
        }
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (this.getClass() != obj.getClass()) {
                return false;
            }
            Pair p = (Pair) obj;
            return this.x==p.x && this.y==p.y;
        }
        public boolean equal(Pair p){
            if(this.x==p.x)
                return this.y==p.y;
            if(this.x==p.y)
                return this.y==p.x;
            else
                return false;
        }
        public Pair clone(){
            return new Pair(x, y);
        }
        public String toString(){
            return this.x+" "+this.y;
        }
        public void add(Pair p){
            x+=p.x;
            y+=p.y;
        }
        public Pair multiply(int x){
            return new Pair(x*this.x, x*this.y);
        }
    }
} Main
import java.io.*;
import java.util.*;

public class Main {
    static PrintWriter pw;
    static Scanner sc;
    static int[] dp;
    static ArrayList<Integer>[] adj;
    static boolean[] visit;
    static long ceildiv(long x, long y) { return (x + y - 1) / y; }
    static int mod(long x, int m) { return (int) ((x % m + m) % m); }
    public static long gcd(long x, long y) {return y == 0 ? x : gcd(y, x % y);}
    public static void main(String[] args) throws Exception {
        sc = new Scanner(System.in);
        pw = new PrintWriter(System.out);
        long x=sc.nextLong();
        StringBuilder sb=new StringBuilder();
        while(x>=1){
            x--;
            sb.append((char)('a'+x%26));
            x/=26;
        }
        pw.println(sb.reverse().toString());
        pw.close();
    }
    static void printArr(int[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    }
    static void printArr(long[] arr) {
        for (int i = 0; i < arr.length - 1; i++)
            pw.print(arr[i] + " ");
        pw.println(arr[arr.length - 1]);
    }
    static void printArr(Integer[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i] + " ");
        pw.println();
    }
    static void printArr(char[] arr) {
        for (int i = 0; i < arr.length; i++)
            pw.print(arr[i]);
        pw.println();
    }
    static void printArr(ArrayList list) {
        for (int i = 0; i < list.size(); i++)
            pw.print(list.get(i) + " ");
        pw.println();
    }
    static class Scanner {
        StringTokenizer st;
        BufferedReader br;
        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public Scanner(FileReader r) {
            br = new BufferedReader(r);
        }

        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }

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

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

        public String nextLine() throws IOException {
            return br.readLine();
        }

        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        public int[] nextArr(int n) throws IOException {
            int[] arr = new int[n];
            for (int i = 0; i < arr.length; i++)
                arr[i] = nextInt();
            return arr;
        }
        public Integer[] nextsort(int n) throws IOException{
            Integer[] arr=new Integer[n];
            for(int i=0; i<n; i++)
                arr[i]=nextInt();
            return arr;
        }
        public Pair nextPair() throws IOException{
            return new Pair(nextInt(), nextInt());
        }
        public Pair[] nextPairArr(int n) throws IOException{
            Pair[] arr=new Pair[n];
            for(int i=0; i<n; i++)
                arr[i]=new Pair(nextInt(), nextInt());
            return arr;
        }
        public boolean ready() throws IOException {
            return br.ready();
        }
    }
    static class Pair implements Comparable<Pair>{
        long x;
        long y;
        public Pair(long x, long y) {
            this.x=x;
            this.y=y;
        }
        public int hashCode() {
            return (int)(this.x*1000+this.y);
        }
        public int compareTo(Pair p){
            return (int)(this.x-p.x);
        }
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (this.getClass() != obj.getClass()) {
                return false;
            }
            Pair p = (Pair) obj;
            return this.x==p.x && this.y==p.y;
        }
        public boolean equal(Pair p){
            if(this.x==p.x)
                return this.y==p.y;
            if(this.x==p.y)
                return this.y==p.x;
            else
                return false;
        }
        public Pair clone(){
            return new Pair(x, y);
        }
        public String toString(){
            return this.x+" "+this.y;
        }
        public void add(Pair p){
            x+=p.x;
            y+=p.y;
        }
        public Pair multiply(int x){
            return new Pair(x*this.x, x*this.y);
        }
    }
}
