1 #include<cstdio>
 2 #include<cmath>
 3 #include<algorithm>
 4 #include<cstring>
 5 #include<string>
 6 #include<iostream>
 7 #include<map>
 8 #include<vector>
 9 #include<set>
10 #include<queue>
11 using namespace std;
12 const int N = 100;
13 int main() {
14     int n, k;
15     char ans[5][N];
16     scanf("%d %d", &n, &k);
17     printf("YES\n");
18     for (int i = 0; i < 5; i++)
19     {
20         for (int j = 0; j < N; j++)
21         {
22             ans[i][j] = '.';
23         }
24     }
25     if (k % 2 == 0)
26     {
27         int p = 2;
28         while (k > 0)
29         {
30             ans[2][p] = '#';
31             ans[3][p] = '#';
32             p++;
33             k -= 2;
34         }
35     }
36     else
37     {
38         if (k == 1)
39         {
40             ans[2][n / 2 + 1] = '#';
41         }
42         else if (k == 3)
43         {
44             int s = (n + 1) / 2;
45             ans[2][s] = '#';
46             ans[2][s - 1] = '#';
47             ans[2][s + 1] = '#';
48         }
49         else
50         {
51             ans[2][2] = '#';
52             ans[2][3] = '#';
53             ans[3][2] = '#';
54             int p = 4;
55             k -= 3;
56             while (k > 0)
57             {
58                 k -= 2;
59                 ans[2][p] = '#';
60                 ans[3][p] = '#';
61                 p++;
62             }
63         }
64     }
65     for (int i = 1; i <= 4; i++)
66     {
67         for (int j = 1; j <= n; j++)
68         {
69             printf("%c", ans[i][j]);
70         }
71         printf("\n");
72     }
73     return 0;
74 }