import qualified Data.Map as Map
import Data.List

f::Int->Int->[Int]
f 1 _=[]
f 2 _=[2]
f 3 _=[3]
f n d
   |n `mod` d==0=d:f (n `div` d) d
   |otherwise=f n (d+1)

h::[Int]->Map.Map Int Int ->[Int]->Int
h [] _ ds=sum (nub ds)
h (x:xs) ms ds
     |(Map.member x ms)==True=let Just y=Map.lookup x ms
                              in h xs ms (y:ds)
     |otherwise=h xs ms ds

f2::Int->[Int]->Map.Map Int Int->Map.Map Int Int
f2 _ [] ms=ms
f2 n (x:xs) ms=let ms2=Map.insert x n ms
               in f2 n xs ms2

g::Int->Int->Map.Map Int Int->Int
g n m ms
   |n>m=sum (nub (Map.elems ms))
g n m ms=let xs=f n 2
             t=h xs ms [0]
             ms2=f2 n xs ms
         in if t>n then g (n+1) m ms 
                   else g (n+1) m ms2

main = do
       e<-getLine
       let n=read e::Int
       print $ g 2 n (Map.fromList [(0::Int,0::Int)])