d = io.read("*n")
a = {}
for i = 0, d do
  a[i] = io.read("*n")
end
for i = d, 3, -1 do
  a[i - 2] = a[i - 2] + a[i]
end
if(a[2] ~= nil and a[2] ~= 0) then
  print(2)
  print(a[0] .. " " .. a[1] .. " " .. a[2])
elseif(a[1] ~= nil and a[1] ~= 0) then
  print(1)
  print(a[0] .. " " .. a[1])
else
  print(0)
  print(a[0])
end