#include <bits/stdc++.h>
using namespace std;
bool Less(const pair<pair<int, int>, int>& s1,
          const pair<pair<int, int>, int>& s2) {
  if (s1.first.first == s2.first.first)
    return s1.first.second > s2.first.second;
  return s1.first.first < s2.first.first;
}
int main() {
  int n, k;
  cin >> n >> k;
  char da[4][200];
  if (n >= 5 && k >= 5)
    cout << "YES" << endl;
  else if (k == 1 || k == 3)
    cout << "YES" << endl;
  else if (k % 2 == 0 || k % (n - 2) == 0)
    cout << "YES" << endl;
  else {
    cout << "NO" << endl;
    return 0;
  }
  if (k % 2 == 0)
    for (int j = 0; j < n; j++) {
      for (int i = 0; i < 4; i++)
        if (k != 0 && j != 0 && j != n - 1 && i != 0 && i != 3)
          da[i][j] = '#', k--;
        else
          da[i][j] = '.';
    }
  else if (k % (n - 2) == 0)
    for (int i = 0; i < 4; i++) {
      for (int j = 0; j < n; j++)
        if (k != 0 && j != 0 && j != n - 1 && i != 0 && i != 3)
          da[i][j] = '#', k--;
        else
          da[i][j] = '.';
    }
  else if (n >= 5 && k >= 5) {
    k = k - 2;
    for (int j = 0; j < n; j++) {
      for (int i = 0; i < 4; i++)
        if (k != 0 && j != 0 && j != n - 1 && i != 0 && i != 3)
          da[i][j] = '#', k--;
        else
          da[i][j] = '.';
    }
    for (int j = 1; j < n; j++)
      if (da[1][j] == '.') {
        da[1][j] = da[2][j] = '#';
        break;
      }
  } else if (k == 1 || k == 3) {
    for (int i = 0; i < 4; i++)
      for (int j = 0; j < n; j++) da[i][j] = '.';
    int j = n / 2;
    if (k == 1)
      da[1][j] = '#';
    else
      da[1][j - 1] = '#', da[1][j] = '#', da[1][j + 1] = '#';
  }
  for (int i = 0; i < 4; i++) {
    for (int j = 0; j < n; j++) cout << da[i][j];
    cout << endl;
  }
  return 0;
}
