#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;
		
		memset(enc, 0, sizeof(char)*10000);
		
		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;
			}			
		}
		*/
		
		int r = 0;
		int pos = 0;
		int shift = 0;
		while (r < velikost) {
			
			enc[pos] = pole[r++];
			pos = pos + key;
			if (pos >= velikost) pos  = ++shift;			
		}
		
		
		/*
		int pos = 0;
		int r = 0;
		int shift = 0;
		for (int u = 0; u < velikost; u++) {
			enc[pos] = pole[r++];
			pos += key;
			if (pos >= velikost) {
				pos %= velikost;
				pos += ++shift;
			} 
		}
		*/
		
		for (int i = 0; i < velikost; i++) {
			printf("%c", enc[i]);
		}
		printf("\n");
		
		
	}
	
	
	return 0;
}