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

int main(void) {
  int N, delka;
  char message[10000];
  char toCipher[10000];
  char cipher[10000];

  int i, j, loop, pointer;

  while (1) {
    scanf("%d\n", &N);
    if (N == 0) break;

    fgets(message, 10000, stdin);

    memset(toCipher, 0, sizeof(toCipher));
    delka = strlen(message);
    j = 0;
    for (i = 0; i < delka; i++) {
      if (message[i] > 32) {
        toCipher[j] = message[i];
        if (toCipher[j] >= 97 && toCipher[j] <= 122)
          toCipher[j] -= 32;
        j++;
      }
    }

    delka = strlen(toCipher);
    memset(cipher, 0, sizeof(cipher));
    loop = 0;
    pointer = 0;
    for (i = 0; i < delka; i++) {
      cipher[pointer] = toCipher[i];
      pointer += N;
      if (pointer >= delka) {
        loop++;
        pointer = loop;
      }
    }
    printf("%s\n", cipher);

  }

  return 0;
}