H,W = map(int,raw_input().split())
h = H/2
hh = H%2
w = W/2
ww = W%2

while True:
    if H == 0 and W == 0:
        break
    for i in range(h):
        print "#."* w + "#"* ww
        print ".#"* w + "."* ww
    if hh == 1:
        print "#."* w + "#"* ww
    print""


         