import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StringWriter;
//CTU Open Programming Contest

public class encipher {
	public static void main(String [] args) throws IOException
	{
		StringWriter writer = new StringWriter();
		BufferedReader bfr = new BufferedReader(new InputStreamReader(System.in));
		String line = bfr.readLine();	
		while(!line.equals("0"))
		{
			int krok = Integer.parseInt(line);
			writer.append(encode(krok,bfr.readLine())+"\n");
			line = bfr.readLine();
		}
		System.out.print(writer);
	}
	
	public static String encode(int krok, String line)
	{
		line = line.replace(" ", "");
		line = line.toUpperCase();
		int delka = line.length();
		char[] code = new char[delka];
		
		int n = 0;
		int pismeno = 0;
		int index = 0;
		while(pismeno != (delka))
		{
			// Mam pismeno 
				char pis = line.charAt(pismeno);
			
				int pozice = n + index*krok;
				if(pozice >= delka)
				{
					n++;
					index = 0;
				} else {
					code[pozice] = pis;
					index++;
					pismeno++;
				}
		}
		
		return arrayToString(code);
	}
	
	public static String arrayToString(char[] array)
	{
		String ret = "";
		for(int i = 0; i<array.length; i++)
			ret += array[i];
		
		return ret;
	}
}