import java.util.*;
import java.io.*;
 
public class Main {
    public static void main(String[] args) throws Exception {
        FastScanner sc = new FastScanner(System.in);
        //long n = 1000000000000001L;
        long n = sc.nextLong();
        char[] alp = "zabcdefghijklmnopqrstuvwxy".toCharArray();
        String ans = "";
        if(n <= 26){
            int index = (int)(n%26);
            System.out.println(alp[index]);
        }else{
            long pow = 1;
            while(n / pow > 0){
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            }
            System.out.println(ans);
        }
    }
}

class FastScanner {
    private BufferedReader reader = null;
    private StringTokenizer tokenizer = null;
    public FastScanner(InputStream in) {
        reader = new BufferedReader(new InputStreamReader(in));
        tokenizer = null;
    }
    
    public void close() throws Exception{
        this.reader.close();
        return;
    }

    public String next() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public String nextLine() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken("\n");
    }

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

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

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

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

    public long[] nextLongArray(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = nextLong();
        return a;
    } 
} import java.util.*; util.* java import java.io.*; io.* java public class Main {
    public static void main(String[] args) throws Exception {
        FastScanner sc = new FastScanner(System.in);
        //long n = 1000000000000001L;
        long n = sc.nextLong();
        char[] alp = "zabcdefghijklmnopqrstuvwxy".toCharArray();
        String ans = "";
        if(n <= 26){
            int index = (int)(n%26);
            System.out.println(alp[index]);
        }else{
            long pow = 1;
            while(n / pow > 0){
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            }
            System.out.println(ans);
        }
    }
} Main public static void main(String[] args) throws Exception {
        FastScanner sc = new FastScanner(System.in);
        //long n = 1000000000000001L;
        long n = sc.nextLong();
        char[] alp = "zabcdefghijklmnopqrstuvwxy".toCharArray();
        String ans = "";
        if(n <= 26){
            int index = (int)(n%26);
            System.out.println(alp[index]);
        }else{
            long pow = 1;
            while(n / pow > 0){
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            }
            System.out.println(ans);
        }
    } main {
        FastScanner sc = new FastScanner(System.in);
        //long n = 1000000000000001L;
        long n = sc.nextLong();
        char[] alp = "zabcdefghijklmnopqrstuvwxy".toCharArray();
        String ans = "";
        if(n <= 26){
            int index = (int)(n%26);
            System.out.println(alp[index]);
        }else{
            long pow = 1;
            while(n / pow > 0){
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            }
            System.out.println(ans);
        }
    } FastScanner sc = new FastScanner(System.in); sc new FastScanner(System.in) long n = sc.nextLong(); n sc.nextLong() sc.nextLong sc char[] alp = "zabcdefghijklmnopqrstuvwxy".toCharArray(); alp "zabcdefghijklmnopqrstuvwxy".toCharArray() "zabcdefghijklmnopqrstuvwxy".toCharArray "zabcdefghijklmnopqrstuvwxy" String ans = ""; ans "" if(n <= 26){
            int index = (int)(n%26);
            System.out.println(alp[index]);
        }else{
            long pow = 1;
            while(n / pow > 0){
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            }
            System.out.println(ans);
        } n <= 26 n 26 {
            int index = (int)(n%26);
            System.out.println(alp[index]);
        } int index = (int)(n%26); index (int)(n%26) n 26 System.out.println(alp[index]) System.out.println System.out System System.out alp[index] alp index {
            long pow = 1;
            while(n / pow > 0){
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            }
            System.out.println(ans);
        } long pow = 1; pow 1 while(n / pow > 0){
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            } n / pow > 0 n / pow n pow 0 {
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            } long i = (n/pow)%26; i (n/pow)%26 (n/pow) n pow 26 int index = (int)i; index (int)i ans = alp[index] + ans ans alp[index] + ans alp[index] alp index ans n -= pow n pow pow *= 26L pow 26L System.out.println(ans) System.out.println System.out System System.out ans String[] args args class FastScanner {
    private BufferedReader reader = null;
    private StringTokenizer tokenizer = null;
    public FastScanner(InputStream in) {
        reader = new BufferedReader(new InputStreamReader(in));
        tokenizer = null;
    }
    
    public void close() throws Exception{
        this.reader.close();
        return;
    }

    public String next() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public String nextLine() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken("\n");
    }

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

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

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

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

    public long[] nextLongArray(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = nextLong();
        return a;
    } 
} FastScanner private BufferedReader reader = null; reader null private StringTokenizer tokenizer = null; tokenizer null public FastScanner(InputStream in) {
        reader = new BufferedReader(new InputStreamReader(in));
        tokenizer = null;
    } FastScanner {
        reader = new BufferedReader(new InputStreamReader(in));
        tokenizer = null;
    } reader = new BufferedReader(new InputStreamReader(in)) reader new BufferedReader(new InputStreamReader(in)) tokenizer = null tokenizer null InputStream in in public void close() throws Exception{
        this.reader.close();
        return;
    } close {
        this.reader.close();
        return;
    } this.reader.close() this.reader.close this.reader this this.reader return; public String next() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    } next {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    } if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        } try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            } catch (IOException e) {
                throw new RuntimeException(e);
            } IOException e {
                throw new RuntimeException(e);
            } throw new RuntimeException(e); new RuntimeException(e) {
                tokenizer = new StringTokenizer(reader.readLine());
            } tokenizer = new StringTokenizer(reader.readLine()) tokenizer new StringTokenizer(reader.readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public String nextLine() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken("\n");
    } nextLine {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken("\n");
    } if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        } try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            } catch (IOException e) {
                throw new RuntimeException(e);
            } IOException e {
                throw new RuntimeException(e);
            } throw new RuntimeException(e); new RuntimeException(e) {
                return reader.readLine();
            } return reader.readLine(); reader.readLine() reader.readLine reader return tokenizer.nextToken("\n"); tokenizer.nextToken("\n") tokenizer.nextToken tokenizer "\n" public long nextLong() {
        return Long.parseLong(next());
    } nextLong {
        return Long.parseLong(next());
    } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next public int nextInt() {
        return Integer.parseInt(next());
    } nextInt {
        return Integer.parseInt(next());
    } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public double nextDouble() {
         return Double.parseDouble(next());
    } nextDouble {
         return Double.parseDouble(next());
    } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next public int[] nextIntArray(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++)
            a[i] = nextInt();
        return a;
    } nextIntArray {
        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 public long[] nextLongArray(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = nextLong();
        return a;
    } nextLongArray {
        long[] a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = nextLong();
        return a;
    } long[] a = new long[n]; a new long[n] n for (int i = 0; i < n; i++)
            a[i] = nextLong(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i a[i] = nextLong(); a[i] = nextLong() a[i] a i nextLong() nextLong return a; a int n n public class Main {
    public static void main(String[] args) throws Exception {
        FastScanner sc = new FastScanner(System.in);
        //long n = 1000000000000001L;
        long n = sc.nextLong();
        char[] alp = "zabcdefghijklmnopqrstuvwxy".toCharArray();
        String ans = "";
        if(n <= 26){
            int index = (int)(n%26);
            System.out.println(alp[index]);
        }else{
            long pow = 1;
            while(n / pow > 0){
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            }
            System.out.println(ans);
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        FastScanner sc = new FastScanner(System.in);
        //long n = 1000000000000001L;
        long n = sc.nextLong();
        char[] alp = "zabcdefghijklmnopqrstuvwxy".toCharArray();
        String ans = "";
        if(n <= 26){
            int index = (int)(n%26);
            System.out.println(alp[index]);
        }else{
            long pow = 1;
            while(n / pow > 0){
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            }
            System.out.println(ans);
        }
    }
} Main
import java.util.*;
import java.io.*;
 
public class Main {
    public static void main(String[] args) throws Exception {
        FastScanner sc = new FastScanner(System.in);
        //long n = 1000000000000001L;
        long n = sc.nextLong();
        char[] alp = "zabcdefghijklmnopqrstuvwxy".toCharArray();
        String ans = "";
        if(n <= 26){
            int index = (int)(n%26);
            System.out.println(alp[index]);
        }else{
            long pow = 1;
            while(n / pow > 0){
                long i = (n/pow)%26;
                int index = (int)i;
                ans = alp[index] + ans;
                n -= pow;
                pow *= 26L;
            }
            System.out.println(ans);
        }
    }
}

class FastScanner {
    private BufferedReader reader = null;
    private StringTokenizer tokenizer = null;
    public FastScanner(InputStream in) {
        reader = new BufferedReader(new InputStreamReader(in));
        tokenizer = null;
    }
    
    public void close() throws Exception{
        this.reader.close();
        return;
    }

    public String next() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public String nextLine() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken("\n");
    }

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

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

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

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

    public long[] nextLongArray(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = nextLong();
        return a;
    } 
}