-- yukicoder My Practice
-- author: Leonardone @ NEETSDKASU

main = readLn >>= print . g 3 . f 4 where
    f k x
        | m > 0     = x
        | otherwise = f k d
        where (d, m) = divMod x k
    g i x
        | x < k     = x
        | otherwise = g (i + 2) (f k x)
        where k = i * i