local read, write = io.read, io.write
local num, nl = '*n', '\n'
local a = read(num)
local x = a
local i = 0
local j = 0
local ans = 0

while i<=x/2 do
 while j <= i do
 if i % j == 0 then
  ans=ans+i
  end
 j = j + 1
 end
i = i + 1
end
if ans == x then
write(ans, nl)
end