from itertools import cycle, islice

gen = lambda w: cycle(("".join(islice(cycle("#."), w)),
                       "".join(islice(cycle(".#"), w))))

def print_lines(h, w):
    for line in islice(gen(w), h):
        print(line)
    print(h, w)

while True:
    s = input()

    if s == "0 0":
        break
    else:
        h, w = list(map(int, s.split()))
        print_lines(h, w)