import java.util.Scanner;

public class encipher {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		for (;;) {
			int n = sc.nextInt();
			sc.nextLine();

			if (n == 0)
				break;

			String str = sc.nextLine();

			str = str.toUpperCase().replace(" ", "");

			int len = str.length();

			boolean[] b = new boolean[len];
			char[] c = new char[len];

			int index = 0;
			int pos = 0;

			boolean first = true;

			while (true) {
				if (first) {
					pos = 0;
					while (b[pos] == true)
						pos++;
					first = false;
				}

				c[pos] = str.charAt(index);
				b[pos] = true;

				index++;

				if (index >= len)
					break;

				pos += n;

				if (pos >= len)
					first = true;

			}
			System.out.println(c);

		}

	}
	/*
	 * 
	 * 2 CTU Open Programming Contest
	 * 
	  
	 
	 */

}