#include <stdio.h>

const int ldiff = 'a' - 'A';

int main() {
	int n, counter, len;
	char buf[10001], res[10001], *bufp = buf;
	char c;
	while (1) {
		scanf("%d\n", &n);
		if (n == 0)
			break;
		bufp = buf;
		while ((c = getchar()) != '\n') {
			if (c != ' ') {
				if (c >= 'A' && c <= 'Z')
					*bufp = c;
				else
					*bufp = c - ldiff;
				++bufp;
			}
		}
		*bufp = '\0';
		
		len = bufp - buf;
		int i, j = 0;
		counter = 0;
		for (i = 0; i < len; ++i) {
			if (j >= len) {
				j = ++counter;
			}
			res[j] = buf[i];
			j += n;
		}
		res[len] = '\0';
		
		printf("%s\n", res);
	}
	return 0;
}