import java.io.*;
import java.util.*;
import java.awt.geom.*;

/**
 * Solution to Zig Zag Nametag
 * 
 * @author vanb
 */
public class zigzag_vanb
{
    public Scanner sc;
    public PrintStream ps;
    
    public String answer = null;
    public StringBuilder buffer = new StringBuilder(1000000);
    

    
    /**
     * Generate an answer string, specifying the last letter, 
     * and whether to the next-to-last letter should go up or down.
     * Test to see if it's better than the best answer we've seen so far.
     * 
     * @param k Sensei's favorite number
     * @param up Up or Down?
     * @param letter Last letter
     */
    public void generateAnswer( int k, boolean up, char letter )
    {
        buffer.setLength( 0 );
        buffer.append( letter );
        
        // Fill in the whole nametag
        while( k>0 )
        {
            // diff is the distance up or down we've got to go
            // for the next letter
            int diff = Math.abs( (int)letter - (up?'z':'a'));
            if( k<=25 ) diff = k;
            else if( k<=50 ) diff = k/2;
            
            // The next letter
            char newletter = (char)(letter + (up?diff:-diff));
            buffer.append( newletter );
            letter = newletter;
            
            // It's possible that the next letter isn't a letter.
            // In that case, we fail.
            if( !Character.isLowerCase( letter ) ) break;
            
            // Prepare for the next iteration.
            // Swap directions, and remove diff from k.
            up = !up;
            k -= diff;
        }
        

        // If we found a solution
        if( k==0 )
        {
            // Check to see if it's the best solution.
            String result = buffer.reverse().toString();
            if( answer==null ) answer = result;
            else if( result.length()<answer.length() ) answer = result;
            else if( result.length()==answer.length() && result.compareTo(answer)<0 ) answer = result;
        }
    }
    
    /**
     * Driver.
     * @throws Exception
     */
    public void doit() throws Exception
    {
        sc = new Scanner( System.in );
        ps = System.out;
        
        int k = sc.nextInt();
        
        if( k<=25 ) answer = "a" + (char)('a'+k);
        else
        {
            generateAnswer( k, true, 'a' );
            generateAnswer( k, true, 'b' );
            generateAnswer( k, false, 'y' );
            generateAnswer( k, false, 'z' );
        }
                
        ps.println( answer );
            
    }
    
    /**
     * @param args
     */
    public static void main( String[] args ) throws Exception
    {
        new zigzag_vanb().doit();
    }   
}