import java.io.*;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        long n=sc.nextLong();
        StringBuilder ans=new StringBuilder();
        long remain=0;
        long qoute=n-1;
  
        while (qoute>=0) {
            remain=qoute%26;
            qoute=(qoute-remain)/26;
            qoute--;
                    
            ans.append((char)(remain+97));
        }
       
        System.out.println(ans.reverse().toString());
    }
}

class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen)
            return true;
        else
            ptr = 0;
        try {
            buflen = in.read(buffer);
        } catch (final IOException e) {
            e.printStackTrace();
        }
        if (buflen <= 0)
            return false;
        return true;
    }

    private int readByte() {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    }

    private static boolean isPrintableChar(final int c) {
        return 33 <= c && c <= 126;
    }

    private void skipUnprintable() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
    }

    public boolean hasNext() {
        skipUnprintable();
        return hasNextByte();
    }

    public String next() {
        final StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b)
            throw new NumberFormatException();
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b))
                return minus ? -n : n;
            else
                throw new NumberFormatException();
            b = readByte();
        }
    }
} import java.io.*; io.* java import java.util.Scanner; Scanner java.util import java.util.StringTokenizer; StringTokenizer java.util public class Main {
    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        long n=sc.nextLong();
        StringBuilder ans=new StringBuilder();
        long remain=0;
        long qoute=n-1;
  
        while (qoute>=0) {
            remain=qoute%26;
            qoute=(qoute-remain)/26;
            qoute--;
                    
            ans.append((char)(remain+97));
        }
       
        System.out.println(ans.reverse().toString());
    }
} Main public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        long n=sc.nextLong();
        StringBuilder ans=new StringBuilder();
        long remain=0;
        long qoute=n-1;
  
        while (qoute>=0) {
            remain=qoute%26;
            qoute=(qoute-remain)/26;
            qoute--;
                    
            ans.append((char)(remain+97));
        }
       
        System.out.println(ans.reverse().toString());
    } main {
        FastScanner sc = new FastScanner();
        long n=sc.nextLong();
        StringBuilder ans=new StringBuilder();
        long remain=0;
        long qoute=n-1;
  
        while (qoute>=0) {
            remain=qoute%26;
            qoute=(qoute-remain)/26;
            qoute--;
                    
            ans.append((char)(remain+97));
        }
       
        System.out.println(ans.reverse().toString());
    } FastScanner sc = new FastScanner(); sc new FastScanner() long n=sc.nextLong(); n sc.nextLong() sc.nextLong sc StringBuilder ans=new StringBuilder(); ans new StringBuilder() long remain=0; remain 0 long qoute=n-1; qoute n-1 n 1 while (qoute>=0) {
            remain=qoute%26;
            qoute=(qoute-remain)/26;
            qoute--;
                    
            ans.append((char)(remain+97));
        } qoute>=0 qoute 0 {
            remain=qoute%26;
            qoute=(qoute-remain)/26;
            qoute--;
                    
            ans.append((char)(remain+97));
        } remain=qoute%26 remain qoute%26 qoute 26 qoute=(qoute-remain)/26 qoute (qoute-remain)/26 (qoute-remain) qoute remain 26 qoute-- qoute ans.append((char)(remain+97)) ans.append ans (char)(remain+97) remain 97 System.out.println(ans.reverse().toString()) System.out.println System.out System System.out ans.reverse().toString() ans.reverse().toString ans.reverse() ans.reverse ans String[] args args class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen)
            return true;
        else
            ptr = 0;
        try {
            buflen = in.read(buffer);
        } catch (final IOException e) {
            e.printStackTrace();
        }
        if (buflen <= 0)
            return false;
        return true;
    }

    private int readByte() {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    }

    private static boolean isPrintableChar(final int c) {
        return 33 <= c && c <= 126;
    }

    private void skipUnprintable() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
    }

    public boolean hasNext() {
        skipUnprintable();
        return hasNextByte();
    }

    public String next() {
        final StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b)
            throw new NumberFormatException();
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b))
                return minus ? -n : n;
            else
                throw new NumberFormatException();
            b = readByte();
        }
    }
} FastScanner private final InputStream in = System.in; in System.in System System.in private final byte[] buffer = new byte[1024]; buffer new byte[1024] 1024 private int ptr = 0; ptr 0 private int buflen = 0; buflen 0 private boolean hasNextByte() {
        if (ptr < buflen)
            return true;
        else
            ptr = 0;
        try {
            buflen = in.read(buffer);
        } catch (final IOException e) {
            e.printStackTrace();
        }
        if (buflen <= 0)
            return false;
        return true;
    } hasNextByte {
        if (ptr < buflen)
            return true;
        else
            ptr = 0;
        try {
            buflen = in.read(buffer);
        } catch (final IOException e) {
            e.printStackTrace();
        }
        if (buflen <= 0)
            return false;
        return true;
    } if (ptr < buflen)
            return true;
        else
            ptr = 0; ptr < buflen ptr buflen return true; true ptr = 0 ptr 0 try {
            buflen = in.read(buffer);
        } catch (final IOException e) {
            e.printStackTrace();
        } catch (final IOException e) {
            e.printStackTrace();
        } final IOException e {
            e.printStackTrace();
        } e.printStackTrace() e.printStackTrace e {
            buflen = in.read(buffer);
        } buflen = in.read(buffer) buflen in.read(buffer) in.read in buffer if (buflen <= 0)
            return false; buflen <= 0 buflen 0 return false; false return true; true private int readByte() {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    } readByte {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    } if (hasNextByte())
            return buffer[ptr++];
        else
            return -1; hasNextByte() hasNextByte return buffer[ptr++]; buffer[ptr++] buffer ptr++ ptr return -1; -1 1 private static boolean isPrintableChar(final int c) {
        return 33 <= c && c <= 126;
    } isPrintableChar {
        return 33 <= c && c <= 126;
    } return 33 <= c && c <= 126; 33 <= c && c <= 126 33 <= c 33 c c <= 126 c 126 final int c c private void skipUnprintable() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
    } skipUnprintable {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
    } while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++; hasNextByte() && !isPrintableChar(buffer[ptr]) hasNextByte() hasNextByte !isPrintableChar(buffer[ptr]) isPrintableChar(buffer[ptr]) isPrintableChar buffer[ptr] buffer ptr ptr++ ptr public boolean hasNext() {
        skipUnprintable();
        return hasNextByte();
    } hasNext {
        skipUnprintable();
        return hasNextByte();
    } skipUnprintable() skipUnprintable return hasNextByte(); hasNextByte() hasNextByte public String next() {
        final StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    } next {
        final StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    } final StringBuilder sb = new StringBuilder(); sb new StringBuilder() int b = readByte(); b readByte() readByte while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        } isPrintableChar(b) isPrintableChar b {
            sb.appendCodePoint(b);
            b = readByte();
        } sb.appendCodePoint(b) sb.appendCodePoint sb b b = readByte() b readByte() readByte return sb.toString(); sb.toString() sb.toString sb public long nextLong() {
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b)
            throw new NumberFormatException();
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b))
                return minus ? -n : n;
            else
                throw new NumberFormatException();
            b = readByte();
        }
    } nextLong {
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b)
            throw new NumberFormatException();
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b))
                return minus ? -n : n;
            else
                throw new NumberFormatException();
            b = readByte();
        }
    } long n = 0; n 0 boolean minus = false; minus false int b = readByte(); b readByte() readByte if (b == '-') {
            minus = true;
            b = readByte();
        } b == '-' b '-' {
            minus = true;
            b = readByte();
        } minus = true minus true b = readByte() b readByte() readByte if (b < '0' || '9' < b)
            throw new NumberFormatException(); b < '0' || '9' < b b < '0' b '0' '9' < b '9' b throw new NumberFormatException(); new NumberFormatException() while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b))
                return minus ? -n : n;
            else
                throw new NumberFormatException();
            b = readByte();
        } true {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b))
                return minus ? -n : n;
            else
                throw new NumberFormatException();
            b = readByte();
        } if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b))
                return minus ? -n : n;
            else
                throw new NumberFormatException(); '0' <= b && b <= '9' '0' <= b '0' b b <= '9' b '9' {
                n *= 10;
                n += b - '0';
            } n *= 10 n 10 n += b - '0' n b - '0' b '0' if (b == -1 || !isPrintableChar(b))
                return minus ? -n : n;
            else
                throw new NumberFormatException(); b == -1 || !isPrintableChar(b) b == -1 b -1 1 !isPrintableChar(b) isPrintableChar(b) isPrintableChar b return minus ? -n : n; minus ? -n : n minus -n n n throw new NumberFormatException(); new NumberFormatException() b = readByte() b readByte() readByte public class Main {
    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        long n=sc.nextLong();
        StringBuilder ans=new StringBuilder();
        long remain=0;
        long qoute=n-1;
  
        while (qoute>=0) {
            remain=qoute%26;
            qoute=(qoute-remain)/26;
            qoute--;
                    
            ans.append((char)(remain+97));
        }
       
        System.out.println(ans.reverse().toString());
    }
} public class Main {
    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        long n=sc.nextLong();
        StringBuilder ans=new StringBuilder();
        long remain=0;
        long qoute=n-1;
  
        while (qoute>=0) {
            remain=qoute%26;
            qoute=(qoute-remain)/26;
            qoute--;
                    
            ans.append((char)(remain+97));
        }
       
        System.out.println(ans.reverse().toString());
    }
} Main
import java.io.*;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        long n=sc.nextLong();
        StringBuilder ans=new StringBuilder();
        long remain=0;
        long qoute=n-1;
  
        while (qoute>=0) {
            remain=qoute%26;
            qoute=(qoute-remain)/26;
            qoute--;
                    
            ans.append((char)(remain+97));
        }
       
        System.out.println(ans.reverse().toString());
    }
}

class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen)
            return true;
        else
            ptr = 0;
        try {
            buflen = in.read(buffer);
        } catch (final IOException e) {
            e.printStackTrace();
        }
        if (buflen <= 0)
            return false;
        return true;
    }

    private int readByte() {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    }

    private static boolean isPrintableChar(final int c) {
        return 33 <= c && c <= 126;
    }

    private void skipUnprintable() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
    }

    public boolean hasNext() {
        skipUnprintable();
        return hasNextByte();
    }

    public String next() {
        final StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b)
            throw new NumberFormatException();
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b))
                return minus ? -n : n;
            else
                throw new NumberFormatException();
            b = readByte();
        }
    }
}