import sys

def main():
    lines = sys.stdin.readlines()

    for line in lines:
        if len(line) == 0:
            continue
        # print(line)
        # rm '\n' from string of a line
        line = line.strip('\n')
        elems = line.split(" ")
        # print elems
        if elems[0] == "0" or elems[1] == "0":
            continue
        for height_ind in range(int(elems[0])):
            width_str = ""
            for width_ind in range(int(elems[1])):
                if ( (height_ind + 1) % 2 == 1 and (width_ind + 1) % 2 == 1 ) or ((height_ind + 1) % 2 == 0 and (width_ind + 1) % 2 == 0):
                    width_str = width_str + "#"
                else:
                    width_str = width_str + "."
            print width_str
        print("")

if __name__ == "__main__":
    main()