/* 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
	{
		// your code goes here
		int n=4;
		for(int i=1;i<=n;i++)
		{
			char ch= (char)('A'+i-1);
			for(int j=1;j<=i;j++)
			{
				System.out.print(ch+" ");
				ch++;
			}
			System.out.println();
		}
		
	}
}