a = 0
while a < 100:
    h, w = map(int, input().split())

    if h == 0 and w == 0:
        break
    elif h == 1 and w == 1:
        print("#")
    elif w % 2 == 0 and h % 2 == 1:
        b = 0
        while b < (h - 2) / 2:
            for i in range(int(w/2)):
                print("#.", end = "")
            print()
            for j in range(int(w/2)):
                print(".#", end = "")
            print()
            b += 1
        for i in range(int(w/2)):
            print("#.", end = "")
        print()
    elif w % 2 == 1 and h % 2 == 1:
        b = 0
        while b <= (h - 2) / 2:
            for i in range(int(w/2)):
                print("#.", end = "")
            print("#")
            for j in range(int(w/2)):
                print(".#", end = "")
            print(".")
            b += 1
        for i in range(int(w/2)):
            print("#.", end = "")
        print("#")
    elif w % 2 == 0 and h % 2 == 0:
        b = 0
        while b < (h - 2) / 2:
            for i in range(int(w/2)):
                print("#.", end = "")
            print()
            for j in range(int(w/2)):
                print(".#", end = "")
            print()
            b += 1
    elif w % 2 == 1 and h % 2 == 0:
        b = 0
        while b < (h - 2) / 2:
            for i in range(int(w/2)):
                print("#.", end = "")
            print("#")
            for j in range(int(w/2)):
                print(".#", end = "")
            print(".")
            b += 1
    print()
    a += 1
