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

#[allow(dead_code)]
fn get_line() -> String {
    let stdin = stdin();
    let mut line = String::new();
    stdin.lock().read_line(&mut line).expect("io error.");
    line.trim().to_string()
}

#[allow(dead_code)]
fn cast<T: FromStr>(s: &str) -> T {
    s.parse().ok().expect("parse error.")
}

#[allow(dead_code)]
fn get_vec<T: FromStr>() -> Vec<T> {
    (&get_line()).split(' ').map(cast::<T>).collect()
}


/* ---------- ここまでテンプレ ---------- */


fn main() {
    let v: Vec<i64> = get_vec();

    let mut ok: i64 = 0;
    let mut ng: i64 = 10_000_001;

    while ng - ok > 1 {
        let mid = (ok + ng) / 2;

        let mut dif: i64 = 0;
        for i in 0..3 {
            if v[i] < mid {
                dif += v[i] - mid;
            } else {
                dif += (v[i] - mid) / 2;
            }
        }

        // println!("{} -> {}", mid, dif);

        if dif >= 0 {
            ok = mid;
        } else {
            ng = mid;
        }
    }

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