#include <bits/stdc++.h>
char ans[5][105];
int main() {
  register int n, k;
  scanf("%d%d", &n, &k);
  printf("YES\n");
  for (int i = 0; i < 5; i++)
    for (int j = 0; j < 105; j++) ans[i][j] = '.';
  if (k % 2 == 0) {
    int p = 2;
    while (k > 0) {
      ans[2][p] = '#';
      ans[3][p] = '#';
      p++;
      k -= 2;
    }
  } else {
    if (k == 1)
      ans[2][n / 2 + 1] = '#';
    else if (k == 3) {
      int s = (n + 1) / 2;
      ans[2][s] = '#';
      ans[2][s - 1] = '#';
      ans[2][s + 1] = '#';
    } else {
      ans[2][2] = '#';
      ans[2][3] = '#';
      ans[3][2] = '#';
      register int p = 4;
      k -= 3;
      while (k > 0) {
        k -= 2;
        ans[2][p] = '#';
        ans[3][p] = '#';
        p++;
      }
    }
  }
  for (register int i = 1; i < 5; i++, puts(""))
    for (register int j = 1; j <= n; j++) putchar(ans[i][j]);
  return 0;
}
