while 1:
        h,w=map(int,input().split())
        if h==w==0:
                break
        p=[[0 for i in range(w)] for j in range(h)]
        for i in range(w):
                for j in range(h):
                        if (i+j)%2=1:
                                p[i][j]=1
        for i in range(w):
                for j in range(h):              
                        if f[i][j]==1:
                                print('#',end='')
                        else :
                                print('.',end='')

