open System
let N = int <| Console.ReadLine()
let A = Array.sort <| Console.ReadLine().Split(' ')

if N % 2 <> 0 then
    printfn "%s" A.[(N-1)/2]
else 
    printfn "%f" ((Double.Parse A.[(N-1)/2] +  Double.Parse A.[N/2]) / 2.)