#include <cstdio>
#include <cstdlib>
#include <cctype>

int main(int argc, char** argv)
{
	
	int key;
	char symbol;
	char pole[10100];
	char enc[10100];
	
	
	while (true) {
		scanf("%d\n", &key);
		if (key == 0) break;
		
		int i = 0;
		while (true) {
			scanf("%c", &symbol);
			if (symbol == '\n') break;
			if (symbol == ' ') continue;
			
			else {
				pole[i] = toupper(symbol);
				i++;
			}		
		}
		
		int velikost = i;
		int r = 0;
		
		for (int j = 0; j < velikost; j++) {
			if (r >= velikost) break;
			
			for (int k = 0; k < velikost; k++) {
				enc[k * key + j] = pole[r++];
				
				if ((k + 1) * key >= velikost) break;
				if (r >= velikost) break;
			}			
		}
		
		for (int i = 0; i < velikost; i++) {
			printf("%c", enc[i]);
		}
		printf("\n");
		
		
	}
	
	
	return 0;
}