n = io.read("*n")
ret = 0LL
for i = 1, n do
  if i % 3 == 1 then
    ret = ret + i
  elseif i % 3 == 2 then
    ret = ret + 1LL * i * i
  else
    ret = ret + 1LL * i * i * i
  end
end
ret = tostring(ret):gsub("LL", "")
print(ret)