fn main() {
    let mut a = input_vector::<f64>();
    a.sort_by_key(|q| OrdFloat(*q));
    println!("{}", (a[1] + a[2]) / a.iter().sum::<f64>());
}

pub mod input {
    use std::io;
    const SPLIT_DELIMITER: char = ' ';

    #[macro_export]
    #[allow(unused_macros)]
    macro_rules! inputm {
    ( $($x:expr ),*) => {
        {
            let temp_str = input_line_str();
            let mut split_result_iter = temp_str.split_whitespace();
                $(
                let buf_split_result = split_result_iter.next();
                let buf_split_result = buf_split_result.unwrap();
                    ($x) = buf_split_result.parse().unwrap();
                )*
        }
    };
}

    pub fn input_line_str() -> String {
        let mut s = String::new();
        io::stdin().read_line(&mut s).unwrap();
        s.trim().to_string()
    }

    pub fn input_vector2d<T>(line: usize) -> Vec<Vec<T>>
    where
        T: std::str::FromStr,
    {
        let mut v: Vec<Vec<T>> = Vec::new();

        for _ in 0..line {
            let vec_line = input_vector();
            v.push(vec_line);
        }
        v
    }

    #[allow(clippy::match_wild_err_arm)]
    pub fn input_vector<T>() -> Vec<T>
    where
        T: std::str::FromStr,
    {
        let mut v: Vec<T> = Vec::new();

        let s = input_line_str();
        let split_result = s.split(SPLIT_DELIMITER);
        for z in split_result {
            let buf = match z.parse() {
                Ok(r) => r,
                Err(_) => panic!("Parse Error",),
            };
            v.push(buf);
        }
        v
    }

    #[allow(clippy::match_wild_err_arm)]
    pub fn input_vector_row<T>(n: usize) -> Vec<T>
    where
        T: std::str::FromStr,
    {
        let mut v = Vec::with_capacity(n);
        for _ in 0..n {
            let buf = match input_line_str().parse() {
                Ok(r) => r,
                Err(_) => panic!("Parse Error",),
            };
            v.push(buf);
        }
        v
    }

    pub trait ToCharVec {
        fn to_charvec(&self) -> Vec<char>;
    }

    impl ToCharVec for String {
        fn to_charvec(&self) -> Vec<char> {
            self.to_string().chars().collect::<Vec<_>>()
        }
    }
}
pub mod ordfloat {
    use std::cmp::Ordering;
    use std::ops::Deref;

    #[derive(PartialEq)]
    pub struct OrdFloat(pub f64);

    impl Ord for OrdFloat {
        fn cmp(&self, other: &Self) -> Ordering {
            self.partial_cmp(&other).unwrap()
        }
    }

    impl PartialOrd for OrdFloat {
        fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
            self.0.partial_cmp(&other.0)
        }
    }

    impl Deref for OrdFloat {
        type Target = f64;

        fn deref(&self) -> &f64 {
            &self.0
        }
    }

    impl Eq for OrdFloat {}
}
use input::*;
use ordfloat::*;