import itertools
from math import isqrt

ceil = lambda a, b: (a + b - 1) // b
ceil_sq = lambda n: 1 + isqrt(n - 1)

N, K = map(int, input().split())
if N < K ** 2:
    M = ceil_sq(N)
    ans = [['.'] * M for _ in range(M)]
    for i, j in itertools.product(range(M), repeat=2):
        if i * M + j >= N:
            break
        ans[i][j] = '#'
else:
    M = ceil(N, K)
    ans = [['.'] * M for _ in range(M)]
    ct = 0
    for i, j in itertools.product(range(M), repeat=2):
        if ct >= N:
            break
        if 0 <= (j - i) % M < K:
            ans[i][j] = '#'
            ct += 1
print(M)
for a in ans:
    print(''.join(map(str, a)))