def solve(h, w):
    a, b = '#', '.'

    for i in range(h):
        row = ''
        flag = True if i % 2 == 0 else False
        for j in range(w):
            if flag:
                row += a
            else:
                row += b
            flag = not flag
        print(row)
    return None


if __name__ == '__main__':
    _input = [
        (3, 4),
        (5, 6),
        (3, 3),
        (0, 0)
    ]

    for h, w in _input:
        solve(h, w)
        print('\n')