/*
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 * and open the template in the editor.
 */
import java.io.*;
/**
 *
 * @author cteam025
 */
public class encipher {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int length; String str; StringBuilder stb; char[] out;
        while((length = readInt(br)) != 0) {
            str = br.readLine();
            stb = new StringBuilder(str.toUpperCase());
            for(int i = 0; i < stb.length(); i++) {
                if(stb.charAt(i) == ' ') {
                    stb = stb.deleteCharAt(i);
                    i--;
                }
            }
            out = new char[stb.length()];
            int i = 0, k = 1;
            //System.out.println(stb);
            for(int j = 0; j < out.length; j++) {
                if(i > out.length) {
                    i = k; k++;
                }
                out[i] = stb.charAt(j);
                i+=length;
            }
            System.out.println(new String(out));
        }
    }
    
    public static int readInt(Reader in) throws IOException {
        int i = 0, j;
        while((j = in.read()) != '\n') {
            if(j == '\r') continue;
            if(j == ' ') break;
            i = (((i << 2) + i) << 1) + (j - 48);
        }
        return i;
    }

}