figure = ''
pattern = ['', '#', '.']
p_selector = 1
height, width = [int(x) for x in input().split()]
while height or width:
    for h in range(height):
        for w in range(weight):
            figure += pattern[p_selector]
            p_selector *= -1
        figure += '\n'
    figure += '\n'
    height, width = [int(x) for x in input().split()]

print(figure[:-1])