H, W = map(int, raw_input().split())

for i in range(H):
  for j in range(W):
    if i%2 == 0:
      if j%2 == 0:
        print "#",
      else:
        print ".",
    else:
      if j%2 == 0:
        print ".",
      else:
        print "#",
  print "\n"

    