h=[]; w=[]; i=0
loop do
  h0,w0=gets.split.map &:to_i
  h0==0&&break
  h<<h0; w<<w0
  i+=1
end
h.size.times do|i|
  h[i].times do|j|
    if j%2==0
      print "#."*(w[i]/2),"#"*(w[i]%2),"\n"
    else
      print ".#"*(w[i]/2),"."*(w[i]%2),"\n"
    end
  end
  print "\n"
end

