use std::io::prelude::*;
use std::io::stdin;
use std::str::FromStr;

fn main() {
    let n: usize = read();
    let mut v: Vec<i32> = (0..n).map(|_| read()).collect();

    v.sort_unstable();
    let mut ans = v[0] as f64;
    for &v_i in v.iter().skip(1) {
        ans = (ans + v_i as f64) / 2.0;
    }

    println!("{}", ans);
}

#[allow(dead_code)]
fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let token: String = stdin
        .lock()
        .bytes()
        .map(|b| b.unwrap() as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().unwrap()
}
