#include <bits/stdc++.h>
using namespace std;
#pragma comment(linker, "/STACK:255000000")
bool firstout = 1;
template <class T>
T &minn(T &a, T b) {
  if (b < a) a = b;
  return a;
}
template <class T>
T &maxx(T &a, T b) {
  if (a < b) a = b;
  return a;
}
int &madd(int &a, int b) {
  a += b;
  if (a >= 1000000007) a -= 1000000007;
  return a;
}
int &msub(int &a, int b) {
  a -= b;
  if (a < 0) a += 1000000007;
  return a;
}
int &mmult(int &a, int b) { return a = (long long)a * b % 1000000007; }
int mdiv(long long a, long long b, long long m) {
  a = (a % m + m) % m;
  b = (b % m + m) % m;
  if (a % b == 0) return a / b;
  return (a + m * mdiv(-a, m, b)) / b;
}
int n, m, q, l;
long long A[1012][4];
char S[1012], SS[1012];
long long D[4];
bool slv(int d) {
  int nn = n - ((d >> 0) & 1) - ((d >> 1) & 1);
  int mm = m - ((d >> 2) & 1) - ((d >> 3) & 1);
  if (nn < 0 || mm < 0) return 0;
  long long x = q;
  if (((d >> 1) & 1) && ((d >> 2) & 1)) x -= D[0];
  if (((d >> 0) & 1) && ((d >> 3) & 1)) x -= D[2];
  if (((d >> 2) & 1) && ((d >> 3) & 1)) x -= D[3];
  if (x < 0) return 0;
  int i, j, k;
  for (i = (0); i < (nn + 1); i += (2)) {
    for (j = (0); j < (mm + 1); j += (2))
      if (i / 2 * D[0] + j / 2 * D[1] == x) break;
    if (j <= mm) break;
  }
  if (i > nn) return 0;
  i /= 2;
  j /= 2;
  if ((d >> 0) & 1) S[0] = 'C';
  if ((d >> 1) & 1) S[n - 1] = 'A';
  if ((d >> 2) & 1) SS[0] = 'C';
  if ((d >> 3) & 1) SS[m - 1] = 'A';
  for (k = (0); k < (i); ++k) {
    S[((d >> 0) & 1) + k + k] = 'A';
    S[((d >> 0) & 1) + k + k + 1] = 'C';
  }
  for (k = (0); k < (j); ++k) {
    SS[((d >> 2) & 1) + k + k] = 'A';
    SS[((d >> 2) & 1) + k + k + 1] = 'C';
  }
  return 1;
}
int main() {
  int i, j, k;
  char c;
  int a, d;
  int ts;
  for (ts = 1; scanf("%"
                     "d",
                     &(l)) > 0;
       ++ts) {
    scanf(
        "%"
        "d",
        &(q));
    scanf(
        "%"
        "d",
        &(n));
    scanf(
        "%"
        "d",
        &(m));
    for (i = (0); i < (4); ++i) A[1][i] = A[2][i] = 0;
    A[1][1] = A[2][1] = 1;
    A[2][0] = 1;
    for (i = (3); i < (l); ++i) {
      for (j = (0); j < (4); ++j) A[i][j] = A[i - 2][j] + A[i - 1][j];
      if (i & 1)
        ++A[i][2];
      else
        ++A[i][3];
    }
    for (i = (0); i < (4); ++i) D[i] = A[l - 1][i];
    for (i = (0); i < (n); ++i) S[i] = 'B';
    S[n] = 0;
    for (i = (0); i < (m); ++i) SS[i] = 'B';
    SS[m] = 0;
    for (k = (0); k < (16); ++k)
      if (slv(k)) break;
    if (k == 16)
      printf(
          "%"
          "s",
          ("Happy new year!")),
          printf("\n"), firstout = 1;
    else
      printf(
          "%"
          "s",
          (S)),
          printf("\n"), firstout = 1,
                        printf(
                            "%"
                            "s",
                            (SS)),
                        printf("\n"), firstout = 1;
  }
  return 0;
}
