use std::io::*;
use std::str::FromStr;
 
fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

fn main(){
    let n = read::<usize>();
    let mut v = vec![0;n];
    let mut ans = 0.0;

    for x in 0..n {
        v[x] = read::<usize>();
    }

    v.sort_unstable();

    ans += (v[0] as f64) / u64::pow(2u64, (n-1) as u32) as f64;
    for x in 1..n {
        ans += (v[x] as f64) / u64::pow(2u64, (n-x) as u32) as f64;
    }

    println!("{}",ans);

}