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#include <cstdio>

long long T[3][3] = {1, 2, 0,
                     0, 2, 1,
                     0, 1, 2};
int main()
{
  long long c, k, n;

  scanf ("%lld%lld", &n, &k);
  if (n < 60 && k > (3 * ((1LL << n) - 1))) // 59
    printf ("NIE");
  else
    for (c = 2; k > 0; n--) {
      c = T[c][(k - 1) / ((1LL << (n < 60 ? n : 60)) - 1)];
      k = (k - 1) % ((1LL << (n < 60 ? n : 60)) - 1);
      putchar ('a' + c);
    }

  return 0;
}