import java.util.Scanner;


public class encipher {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n;
		String message;
		while ((n = sc.nextInt()) != 0) {
			sc.nextLine();
			message = sc.nextLine();
			
			message = message.toUpperCase().replace(" ", "");
			//System.out.println(message.charAt(0));
			
			int i = 0;
			int zi = 0;
			int zaciatok = 0;
			int vz = message.length();
			char[] vysledok = new char[vz];
			
			while (zi < vz) {
				i = zaciatok++;
				while (i < vz) {
					vysledok[i] = message.charAt(zi);
					i += n;
					zi++;
				}
			}
		
			System.out.println(vysledok);
		}
	}

}