loop do
arr = gets.split.map(&:to_i)
h = arr[0]
w = arr[1]
if h != 0 || w != 0 then
for i in 1..h
for j in 1..w
if j != w then
if (j % 2) == (i % 2) then
print "#"
else
print "."
end
else
if (w % 2) == (i % 2) then
puts "#"
else
puts "."
end
end
end
if i == h then
puts ""
end
end
else
exit
end
end
