# coding : utf-8
while True:
    H, W = map (int, input().split())
    if H == 0 and W == 0:
        break
    for i in range(H):
        for j in range(W):
            if (i + j) % 2 == 0:
                print ('#', end = '')
            else:
                print (' ', end = '')
        print ('')
    if i == H-1:
        print ('')
