a=["#." * (300//2),".#" * (300//2)]*(300//2)
while True:
    [h,w] = map(int, input().split())
    if h==0 and w==0:
        break
    t = map(lambda x: x[0:w], (a[0:h]))
    for i in t:
        print(i)
    print()
78a59a3c167ed099bb9f371077d0e34fc558d94b
<mask token>

<mask token>
while True:
    [h, w] = map(int, input().split())
    if h == 0 and w == 0:
        break
    t = map(lambda x: x[0:w], a[0:h])
    for i in t:
        print(i)
    print()

a = ['#.' * (300 // 2), '.#' * (300 // 2)] * (300 // 2)
while True:
    [h, w] = map(int, input().split())
    if h == 0 and w == 0:
        break
    t = map(lambda x: x[0:w], a[0:h])
    for i in t:
        print(i)
    print()

a=["#." * (300//2),".#" * (300//2)]*(300//2)
while True:
    [h,w] = map(int, input().split())
    if h==0 and w==0:
        break
    t = map(lambda x: x[0:w], (a[0:h]))
    for i in t:
        print(i)
    print()