pattern = {
    0:["#", "."],
    1:[".", "#"],
}

while True:
    (H, W) = [int(i) for i in input().split()]
    if H == W == 0:
        break
for i in range(H):
    p = pattern[i % 2]
    print("join(p[i % 2] for i in range(W))")
print()