import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Scanner;

public class encipher {
	public static void main(String[] args) {
		int a;
		String str;

		Scanner sc = new Scanner(System.in);

		while (true) {

			a = sc.nextInt();
			//System.out.println(a);

			if (a == 0) {
				// System.out.println("konec");
				break;
			}

			sc.nextLine();
			str = sc.nextLine().toUpperCase().trim().replace(" ", "");

			// str.trim();
			// str.toUpperCase();

			//System.out.println(str);

			//System.out.println(str.length());
			char[] pole = new char[str.length()];

			int b = 0;

			for (int i = 0; i < a; i++) {
				for (int j = 0; j < pole.length; j++) {
					if (i + j * a < pole.length) {
						pole[i + j * a] = str.charAt(b);
						b++;
					}
				}

			}

			for (int i = 0; i < pole.length; i++) {
				System.out.print(pole[i]);

			}
			System.out.println();
		}

	}
}