use std::{cmp, io, u32};
fn main() {
    let mut s = String::new();
    io::stdin().read_line(&mut s).expect("read error");
    let n: u32 = s.trim().parse().expect("parse error");

    let mut v = vec![0; 2usize.pow(n)];
    for i in 0..n {
        s.clear();
        io::stdin().read_line(&mut s).expect("read error");
        for (j, x) in s.trim().split_whitespace().enumerate() {
            v[2usize.pow(i as u32) | 2usize.pow(j as u32)] = cmp::max(x.parse().expect("parse error"), 0);
        }
    }

    let mut m: u32 = 2;
    while m <= n {
        for i in 1..v.len() {
            for j in i+1..v.len() {
                let idx = i | j;
                if i.count_ones() + j.count_ones() == m && idx.count_ones() == m {
                    v[idx] = cmp::max(v[idx], v[i] + v[j]);
                }
            }
        }
        m += 2;
    }
    println!("{}", v.last().unwrap());
}