#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

int main(void)
{
	int n;
	char r[10000];
	int rn;
	char c;
	char t[10000];

	for (;;)
	{
		int i = 0, j = 0, k = 0;

		scanf("%d", &n);

		if (n == 0)
		{
			break;
		}

		rn = 0;

		while ((c = getchar()) != '\n');

		while ((c = getchar()) != '\n')
		{
			if (c == ' ')
				continue;

			r[rn ++] = toupper(c);
		}

		r[rn] = '\0';

		for (k = 0; k < n; k ++)
		{
			for (i = 0; i < rn; i += n)
			{
				t[i+k] = r[j ++];
			}		
		}

		printf("%s\n", t);
	}

	return 0;

}