/* package whatever; // don't place package name! */

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

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		char c = 'a';
		for (int i = 1; i < 31; i +=2) {
			System.out.print(new String(new char[40-i/2]).replace("\0", " "));
			System.out.println(new String(new char[i]).replace("\0", c +""));
			c++;
		}
	}
}