import java.io.BufferedReader;
import java.io.InputStreamReader;

public class encipher {

	public static void main(String[] args) throws Exception {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String vstup = in.readLine(); 
			int n = Integer.valueOf(vstup);
			if(n ==0)break;
			String vt = in.readLine();
			vt = vt.replaceAll(" ", "");
			vt = vt.toUpperCase();
			if (n>=vt.length()){
				System.out.println(vt);
				continue;
			}
			String[] pole = new String[vt.length()];
			for(int i = 0;i<pole.length;i++){
				pole[(i*n)%vt.length()] = vt.substring(i, i+1);
			}
			for(int i = 0;i<pole.length;i++){
				System.out.print(pole[i]);
			}
			System.out.println();
		}
	}

}