fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_one<T: std::str::FromStr>() -> Option<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok()
}

fn main() {
    let count: u64 = read();

    let mut numbers: Vec<u64> = vec![];
    for _i in 0..count {
        let input: Option<u64> = read_one();
        if input.is_none() {
            println!("\"assert\"");
            std::process::exit(0);
        }
        numbers.push(input.unwrap());
    }

    let mut new_numbers = vec![];
    for i in 0..numbers.len() {
        for j in 0..numbers.len() {
            if i == j {
                continue;
            }
            let n = numbers[i] + numbers[j];
            if !new_numbers.contains(&n) {
                new_numbers.push(n);
            }
        }
    }
    new_numbers.sort_by(|a, b| b.partial_cmp(a).unwrap());
    println!("{}", new_numbers[1]);
}