#include <bits/stdc++.h>
using namespace std;
int f[57], x, n, m, k;
int main() {
  cin >> k >> x >> n >> m;
  for (int i = 0; i <= n; ++i)
    for (int j = 0; j <= m; ++j)
      for (int t1 = 0; t1 < 4; ++t1)
        for (int t2 = 0; t2 < 4; ++t2) {
          bool ok = 1;
          f[1] = i, f[2] = j,
          f[3] = f[1] + f[2] + ((t1 == 1 || t1 == 3) && (t2 == 2 || t2 == 3));
          for (int p = 4; p <= k; ++p) {
            if (f[p - 2] > x - f[p - 1]) {
              ok = 1;
              break;
            }
            f[p] = f[p - 2] + f[p - 1];
            if (p % 2 && (t2 == 3)) ++f[p];
            if (p % 2 == 0 && (t2 == 1 || t2 == 3) && (t1 == 2 || t1 == 3))
              ++f[p];
          }
          if (f[k] == x && ok) {
            string s1 = "", s2 = "";
            if (t1 == 0) {
              if (i * 2 > n) continue;
              for (int p = 1; p <= i; ++p) s1 += "AC";
              while (s1.size() < n) s1 += "M";
            }
            if (t1 == 1) {
              if (i * 2 + 1 > n) continue;
              for (int p = 1; p <= i; ++p) s1 += "AC";
              while (s1.size() + 1 < n) s1 += "M";
              s1 += "A";
            }
            if (t1 == 2) {
              if (i * 2 + 1 > n) continue;
              s1 += "C";
              for (int p = 1; p <= i; ++p) s1 += "AC";
              while (s1.size() < n) s1 += "M";
            }
            if (t1 == 3) {
              if (i * 2 + 2 > n) continue;
              s1 += "C";
              for (int p = 1; p <= i; ++p) s1 += "AC";
              while (s1.size() + 1 < n) s1 += "M";
              s1 += "A";
            }
            if (t2 == 0) {
              if (j * 2 > m) continue;
              for (int p = 1; p <= j; ++p) s2 += "AC";
              while (s2.size() < m) s2 += "M";
            }
            if (t2 == 1) {
              if (j * 2 + 1 > m) continue;
              for (int p = 1; p <= j; ++p) s2 += "AC";
              while (s2.size() + 1 < m) s2 += "M";
              s2 += "A";
            }
            if (t2 == 2) {
              if (j * 2 + 1 > m) continue;
              s2 += "C";
              for (int p = 1; p <= j; ++p) s2 += "AC";
              while (s2.size() < m) s2 += "M";
            }
            if (t2 == 3) {
              if (j * 2 + 2 > m) continue;
              s2 += "C";
              for (int p = 1; p <= j; ++p) s2 += "AC";
              while (s2.size() + 1 < m) s2 += "M";
              s2 += "A";
            }
            cout << s1 << "\n" << s2 << "\n";
            return 0;
          }
        }
  cout << "Happy new year!";
  return 0;
}
