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;
		List<Integer> positions = new ArrayList<Integer>();
		int key = 0;	
		s = s.replace(" ","");
		String ss = s;
		String end = "";
		while(s.length() != 0 && ss.length() != positions.size())
		{
			end += s.charAt(0);	
			boolean add = true;
			for(int i : positions){
				if(i == key)
				{
					add = false;
				}
			}
			if(add){
				positions.add(key);
			}
			for(int i=1; i<s.length(); i++)
			{
				if((i % (num+1)) == 0 && i >= num)
				{
					
					if(ss.length() != positions.size()){
						end += s.charAt(i);
						boolean adds = true;
						for(int j : positions){
							if(j == i+key)
							{
								adds = false;
							}
						}
						if(add){
							positions.add(key);
						}
					}
				}
			}
			s = s.substring(1,s.length());
			key++;

		}		
		return end.toUpperCase();
	}
}