from __future__ import print_function
while(1):
    x = raw_input()
    if(x == "0 0"):
        break
    x = x.split(" ")
    h = int(x[0])
    w = int(x[1])
    count = 0
    count2 = 0
    for i in range(0,h):
        if(count2 < h):
            count = 0
            for j in range(0,w):
                if(count < w):
                    print("#",end="")
                else:
                    break
                count += 1
                if(count < w):
                    print(".",end="")
                else:
                    break
                count += 1
            print("\n",end="")
        else:
            print("\n",end="")
            break
        count2 += 1
        if(count2 < h):
            count = 0
            for k in range(0,w):
                if(count < w):
                    print(".",end="")
                else:
                    break
                count += 1
                if(count < w):
                    print("#",end="")
                else:
                    break
                count += 1
            print("\n",end="")
        else:
            print("\n",end="")
            break
        count2 += 1
