#include <bits/stdc++.h>
using namespace std;
long long acs[101], fc[101], ba[101], fa[101], bc[101];
long long k, x, n, m;
bool ok(int a, int b, int q, int w) {
  acs[1] = a;
  acs[2] = b;
  fc[1] = fc[2] = ba[1] = ba[2] = 0;
  if (q & 1) fc[1] = 1;
  if (w & 1) ba[1] = 1;
  if (q & 2) fc[2] = 1;
  if (w & 2) ba[2] = 1;
  for (int i = 3; i <= k; ++i) {
    acs[i] = acs[i - 1] + acs[i - 2] + (ba[i - 2] and fc[i - 1]);
    fc[i] = fc[i - 2];
    ba[i] = ba[i - 1];
    if (fc[i] > x) return false;
  }
  return acs[k] == x;
}
int main() {
  cin >> k >> x >> n >> m;
  for (int k = 0; k < 4; ++k)
    for (int l = 0; l < 4; ++l)
      for (int fac = 0; fac <= n >> 1; ++fac) {
        for (int bac = 0; bac <= m >> 1; ++bac) {
          if (ok(fac, bac, k, l)) {
            string a(""), b("");
            int alen = n, blen = m, aa = fac, bb = bac;
            if (fc[1]) {
              a.push_back('C');
              --alen;
            }
            if (fc[2]) {
              b.push_back('C');
              --blen;
            }
            while (aa--) {
              alen -= 2;
              a += "AC";
            }
            while (bb--) {
              blen -= 2;
              b += "AC";
            }
            if (alen < 0 || blen < 0) continue;
            while (blen--) b.push_back('W');
            if (ba[2])
              if (b.back() == 'C')
                continue;
              else
                b[m - 1] = 'A';
            while (alen--) a.push_back('W');
            if (ba[1])
              if (a.back() == 'C')
                continue;
              else
                a[n - 1] = 'A';
            cout << a << '\n' << b << '\n';
            return 0;
          }
        }
      }
  cout << "Happy new year!\n";
}
