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

public class encipher{

public static void main(String[] args) throws IOException{
BufferedReader r=new BufferedReader(new InputStreamReader(System.in));

while(true){
String s = r.readLine();
if(s.equals("0")){
break;
}

int delka = Integer.parseInt(s);
String text = r.readLine();

text = text.replaceAll(" ","");

System.out.println(algorithm(delka, text).toUpperCase());

}

}

public static String algorithm(int delka, String text){

StringBuffer sb = new StringBuffer(text.length());
sb.append(text);
int zacatek=0;
int pozice=0;

for(int i=zacatek; i<20001; i=i + delka){
	if(i>text.length()-1){
	zacatek++;
	i=zacatek;
	}
	if(zacatek>=delka || zacatek>text.length() - 1){
	break;
	}

sb.setCharAt(i, text.charAt(pozice++));


	}


return sb.toString();
}

}