#include <bits/stdc++.h>
using namespace std;
int k;
int x, n, m;
long long s1[55], s2[55], s12[55], s21[55], s22[55], s11[55];
int main() {
  cin >> k >> x >> n >> m;
  int t11 = 1;
  int t12 = 1;
  int t21 = 2;
  int t22 = 2;
  s1[0] = 1;
  s1[1] = 0;
  s2[1] = 1;
  s2[0] = 0;
  s12[0] = 0;
  s12[1] = 0;
  s21[0] = 0;
  s21[1] = 0;
  s11[0] = 0;
  s11[1] = 0;
  s22[0] = 0;
  s22[1] = 0;
  for (int i = 2; i < k; i++) {
    s1[i] = s1[i - 2] + s1[i - 1];
    s2[i] = s2[i - 2] + s2[i - 1];
    s12[i] = s12[i - 2] + s12[i - 1];
    s21[i] = s21[i - 2] + s21[i - 1];
    s12[i] = s12[i - 2] + s12[i - 1];
    s22[i] = s22[i - 2] + s22[i - 1];
    int t31 = t11;
    int t32 = t22;
    if (t12 == t21) {
      if (t12 == 1)
        s11[i]++;
      else
        s22[i]++;
    } else {
      if (t12 == 1)
        s12[i]++;
      else
        s21[i]++;
    }
    t11 = t21;
    t12 = t22;
    t21 = t31;
    t22 = t32;
  }
  bool done = 0;
  if (m == 1) {
    if (n == 1) {
      if (x == s12[k - 1]) {
        cout << "A" << endl;
        cout << "C" << endl;
        done = 1;
      } else if (x == s21[k - 1]) {
        cout << "C" << endl;
        cout << "A" << endl;
        done = 1;
      } else {
        cout << "Happy new year!" << endl;
        done = 1;
      }
    } else {
      int tmp = x;
      for (int j = 0; j <= n; j += 2) {
        x = tmp - s1[k - 1] * j / 2;
        if (x < 0) continue;
        if (n - j > 0 && (x - s12[k - 1]) % s2[k - 1] == 0 &&
            (x - s12[k - 1]) / s2[k - 1] <= (m - 1) / 2) {
          for (int i = 0; i < j / 2; i++) cout << "AC";
          for (int i = 0; i < n - j - 1; i++) cout << "K";
          cout << "A";
          cout << endl;
          cout << "C";
          for (int i = 0; i < (x - s12[k - 1]) / s2[k - 1]; i++) cout << "AC";
          for (int i = 0; i < m - 1 - 2 * ((x - s12[k - 1]) / s2[k - 1]); i++)
            cout << "K";
          cout << endl;
          done = 1;
        } else if (n - j > 0 && (x - s21[k - 1]) % s2[k - 1] == 0 &&
                   (x - s21[k - 1]) / s2[k - 1] <= (m - 1) / 2) {
          cout << "C";
          for (int i = 0; i < j / 2; i++) cout << "AC";
          for (int i = 0; i < n - j - 1; i++) cout << "K";
          cout << endl;
          for (int i = 0; i < (x - s21[k - 1]) / s2[k - 1]; i++) cout << "AC";
          for (int i = 0; i < m - 1 - 2 * ((x - s21[k - 1]) / s2[k - 1]); i++)
            cout << "K";
          cout << "A" << endl;
          done = 1;
        }
        if (done) break;
      }
    }
  } else {
    int tmp = x;
    for (int j = 0; j <= n; j += 2) {
      x = tmp - s1[k - 1] * j / 2;
      if (x < 0) continue;
      if (x % s2[k - 1] == 0 && x / s2[k - 1] <= m / 2) {
        for (int i = 0; i < j / 2; i++) cout << "AC";
        for (int i = 0; i < n - j; i++) cout << "K";
        cout << endl;
        for (int i = 0; i < x / s2[k - 1]; i++) cout << "AC";
        for (int i = 0; i < m - 2 * (x / s2[k - 1]); i++) cout << "K";
        cout << endl;
        done = 1;
      } else if (n - j > 0 && (x - s12[k - 1]) % s2[k - 1] == 0 &&
                 (x - s12[k - 1]) / s2[k - 1] <= (m - 1) / 2) {
        for (int i = 0; i < j / 2; i++) cout << "AC";
        for (int i = 0; i < n - j - 1; i++) cout << "K";
        cout << "A";
        cout << endl;
        cout << "C";
        for (int i = 0; i < (x - s12[k - 1]) / s2[k - 1]; i++) cout << "AC";
        for (int i = 0; i < m - 1 - 2 * ((x - s12[k - 1]) / s2[k - 1]); i++)
          cout << "K";
        cout << endl;
        done = 1;
      } else if ((x - s22[k - 1]) % s2[k - 1] == 0 &&
                 (x - s22[k - 1]) / s2[k - 1] <= (m - 2) / 2) {
        for (int i = 0; i < j / 2; i++) cout << "AC";
        for (int i = 0; i < n - j; i++) cout << "K";
        cout << endl;
        cout << "C";
        for (int i = 0; i < (x - s22[k - 1]) / s2[k - 1]; i++) cout << "AC";
        for (int i = 0; i < m - 2 - 2 * ((x - s22[k - 1]) / s2[k - 1]); i++)
          cout << "K";
        cout << "A" << endl;
        done = 1;
      } else if (n - j > 0 && (x - s21[k - 1]) % s2[k - 1] == 0 &&
                 (x - s21[k - 1]) / s2[k - 1] <= (m - 1) / 2) {
        cout << "C";
        for (int i = 0; i < j / 2; i++) cout << "AC";
        for (int i = 0; i < n - j - 1; i++) cout << "K";
        cout << endl;
        for (int i = 0; i < (x - s21[k - 1]) / s2[k - 1]; i++) cout << "AC";
        for (int i = 0; i < m - 1 - 2 * ((x - s21[k - 1]) / s2[k - 1]); i++)
          cout << "K";
        cout << "A" << endl;
        done = 1;
      } else if (n - j > 0 && (x - s22[k - 1] - s21[k - 1]) % s2[k - 1] == 0 &&
                 (x - s22[k - 1] - s21[k - 1]) / s2[k - 1] <= (m - 2) / 2) {
        cout << "C";
        for (int i = 0; i < j / 2; i++) cout << "AC";
        for (int i = 0; i < n - j - 1; i++) cout << "K";
        cout << endl;
        cout << "C";
        for (int i = 0; i < (x - s22[k - 1] - s21[k - 1]) / s2[k - 1]; i++)
          cout << "AC";
        for (int i = 0;
             i < m - 2 - 2 * ((x - s22[k - 1] - s21[k - 1]) / s2[k - 1]); i++)
          cout << "K";
        cout << "A" << endl;
        done = 1;
      } else if (n - j > 0 &&
                 (x - s22[k - 1] - s21[k - 1] - s12[k - 1]) % s2[k - 1] == 0 &&
                 (x - s22[k - 1] - s21[k - 1] - s12[k - 1]) / s2[k - 1] <=
                     (m - 2) / 2) {
        cout << "C";
        for (int i = 0; i < j / 2; i++) cout << "AC";
        for (int i = 0; i < n - j - 2; i++) cout << "K";
        cout << "A";
        cout << endl;
        cout << "C";
        for (int i = 0; i < (x - s22[k - 1] - s21[k - 1]) / s2[k - 1]; i++)
          cout << "AC";
        for (int i = 0;
             i < m - 2 - 2 * ((x - s22[k - 1] - s21[k - 1]) / s2[k - 1]); i++)
          cout << "K";
        cout << "A" << endl;
        done = 1;
      }
      if (done) break;
    }
  }
  if (!done) {
    cout << "Happy new year!" << endl;
  }
  return 0;
}
