{-# OPTIONS_GHC -O2 -optc-O2 #-}
-- solution for: http://codeforces.com/problemset/problem/200/B
import Data.Char (isSpace)
import qualified Data.ByteString as BS
import qualified Data.ByteString.Char8 as BSC
solve :: Int -> [Int] -> Float
solve n x = sum (map fromIntegral x) / fromIntegral n
main =
do all <- BS.getContents
let Just (n, r1) = readInt all
let (x, _) = readMany readInt r1
print (solve n x)
where readInt s = BSC.readInt (BSC.dropWhile isSpace s)
readInteger s = BSC.readInteger (BSC.dropWhile isSpace s)
readMany readf s = case readf s of
Just (x, r) -> let (xs, t) = readMany readf r
in (x : xs, t)
Nothing -> ([], s)