use std::io::{self, Read};

fn read_stdin() -> Vec<String> {
    let mut buffer = String::new();
    io::stdin().read_to_string(&mut buffer).ok();
    buffer.trim().split('\n').map(|s| s.to_string()).collect()
}

fn main() {
    let input = read_stdin();
    let n = &input[0].parse::<usize>().unwrap();
    let mut nums = input[1].split(' ').map(|s| s.parse::<isize>().unwrap()).collect::<Vec<isize>>();
    nums.sort();

    let result: f64 = if n % 2 == 1 {
        *&nums[*n / 2] as f64
    } else {
        let r = &nums[*n / 2 - 1..*n / 2 + 1];
        let total = r.iter().sum::<isize>() as f64;
        total / 2.0
    };
    println!("{}", result);
}