while True:
    h,w = map(int,input().split())
    for i in range(h):
        if i%2 ==0:
            for j in range(w):
                if j%2 ==0:
                    print('#')
                else:
                    print('.')
        else:
            for j in range(w):
                if j%2 ==0:
                    print('.')
                else:
                    print('#')
    print('')
