import java.util.*;
import java.*;

public class encipher
{
	public static void main(String[] args)
	{	for(;;){
			try{			
				String text = "";
				char znak;
				int num = System.in.read() - '0';			
				int in = System.in.read();
				while(in != '\n'){
					num =  num * 10 + (in - '0');
					in = System.in.read();
				}
						
				if (num == 0) break;
				znak = (char)System.in.read();
				while(znak != '\n')
				{	
					text += znak;
					znak = (char)System.in.read();
							
				}
				String s = encryptItBaby(text,num);
				System.out.println(s);
			}catch(Exception e){}
		}
	}

	private static String encryptItBaby(String text, int num)
	{
		String s = text;
		
		s = s.replace(" ","");
		String ss = s;
		String end = "";
		while(s.length() != 0 && ss.length() != end.length())
		{
			end += s.charAt(0);	
			for(int i=1; i<s.length(); i++)
			{
				if((i % (num+1)) == 0 && i >= num)
				{
					
					if(ss.length() != end.length()){
						end += s.charAt(i);
					}
				}
			}
			s = s.substring(1,s.length());

		}		
		return end.toUpperCase();
	}
}