fn run() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    let mut it = s.trim().split_whitespace();
    let mut x: usize = it.next().unwrap().parse().unwrap();
    let mut y: usize = it.next().unwrap().parse().unwrap();
    let mut z: usize = it.next().unwrap().parse().unwrap();
    if x < y {
        let v = std::cmp::min(y - x, z);
        z -= v;
        x += v;
    } else {
        let v = std::cmp::min(x - y, z);
        z -= v;
        y += v;
    }
    let ans = std::cmp::min(x, y) + z / 2;
    println!("{}", ans);
}

fn main() {
    run();
}