while(True):
    h,w = [int(i) for i in input().split()]
    if(h == 0 and w == 0):
        break
    for i in range(h):
        for j in range(w - 1):
            if(i == 0 or i % 2 == 0):
                if(j == 0 or j % 2 == 0):
                    print('#',end = '')
                else:
                    print('.',end = '')
            if(i % 2 != 0):
                if(j % 2 != 0):
                    print('#',end = '')
                else:
                    print('.',end = '')
        if(i % 2 != 0 and w % 2 == 0):
            print('#')
        elif(h == 1 and w == 1):
            print('#')
        else:
            print('.')
    print('')