#[doc = " https://github.com/hatoo/competitive-rust-snippets"]
#[allow(unused_imports)]
use std::cmp::{max, min, Ordering};
#[allow(unused_imports)]
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};
#[allow(unused_imports)]
use std::io::{stdin, stdout, BufWriter, Write};
#[allow(unused_imports)]
use std::iter::FromIterator;
#[macro_export]
macro_rules ! dvec { ( $ t : expr ; $ len : expr ) => { vec ! [ $ t ; $ len ] } ; ( $ t : expr ; $ len : expr , $ ( $ rest : expr ) ,* ) => { vec ! [ dvec ! ( $ t ; $ ( $ rest ) ,* ) ; $ len ] } ; }
#[allow(unused_macros)]
macro_rules ! debug { ( $ ( $ a : expr ) ,* ) => { eprintln ! ( concat ! ( $ ( stringify ! ( $ a ) , " = {:?}, " ) ,* ) , $ ( $ a ) ,* ) ; } }
#[macro_export]
macro_rules ! input { ( source = $ s : expr , $ ( $ r : tt ) * ) => { let mut parser = Parser :: from_str ( $ s ) ; input_inner ! { parser , $ ( $ r ) * } } ; ( parser = $ parser : ident , $ ( $ r : tt ) * ) => { input_inner ! { $ parser , $ ( $ r ) * } } ; ( new_stdin_parser = $ parser : ident , $ ( $ r : tt ) * ) => { let stdin = std :: io :: stdin ( ) ; let reader = std :: io :: BufReader :: new ( stdin . lock ( ) ) ; let mut $ parser = Parser :: new ( reader ) ; input_inner ! { $ parser , $ ( $ r ) * } } ; ( $ ( $ r : tt ) * ) => { input ! { new_stdin_parser = parser , $ ( $ r ) * } } ; }
#[macro_export]
macro_rules ! input_inner { ( $ parser : ident ) => { } ; ( $ parser : ident , ) => { } ; ( $ parser : ident , $ var : ident : $ t : tt $ ( $ r : tt ) * ) => { let $ var = read_value ! ( $ parser , $ t ) ; input_inner ! { $ parser $ ( $ r ) * } } ; }
#[macro_export]
macro_rules ! read_value { ( $ parser : ident , ( $ ( $ t : tt ) ,* ) ) => { ( $ ( read_value ! ( $ parser , $ t ) ) ,* ) } ; ( $ parser : ident , [ $ t : tt ; $ len : expr ] ) => { ( 0 ..$ len ) . map ( | _ | read_value ! ( $ parser , $ t ) ) . collect ::< Vec < _ >> ( ) } ; ( $ parser : ident , chars ) => { read_value ! ( $ parser , String ) . chars ( ) . collect ::< Vec < char >> ( ) } ; ( $ parser : ident , usize1 ) => { read_value ! ( $ parser , usize ) - 1 } ; ( $ parser : ident , $ t : ty ) => { $ parser . next ::<$ t > ( ) . expect ( "Parse error" ) } ; }
use std::io;
use std::io::BufRead;
use std::str;
pub struct Parser<R> {
    reader: R,
    buf: Vec<u8>,
    pos: usize,
}
impl Parser<io::Empty> {
    pub fn from_str(s: &str) -> Parser<io::Empty> {
        Parser {
            reader: io::empty(),
            buf: s.as_bytes().to_vec(),
            pos: 0,
        }
    }
}
impl<R: BufRead> Parser<R> {
    pub fn new(reader: R) -> Parser<R> {
        Parser {
            reader: reader,
            buf: vec![],
            pos: 0,
        }
    }
    pub fn update_buf(&mut self) {
        self.buf.clear();
        self.pos = 0;
        loop {
            let (len, complete) = {
                let buf2 = self.reader.fill_buf().unwrap();
                self.buf.extend_from_slice(buf2);
                let len = buf2.len();
                if len == 0 {
                    break;
                }
                (len, buf2[len - 1] <= 0x20)
            };
            self.reader.consume(len);
            if complete {
                break;
            }
        }
    }
    pub fn next<T: str::FromStr>(&mut self) -> Result<T, T::Err> {
        loop {
            let mut begin = self.pos;
            while begin < self.buf.len() && (self.buf[begin] <= 0x20) {
                begin += 1;
            }
            let mut end = begin;
            while end < self.buf.len() && (self.buf[end] > 0x20) {
                end += 1;
            }
            if begin != self.buf.len() {
                self.pos = end;
                return str::from_utf8(&self.buf[begin..end]).unwrap().parse::<T>();
            } else {
                self.update_buf();
            }
        }
    }
}
#[allow(unused_macros)]
macro_rules ! debug { ( $ ( $ a : expr ) ,* ) => { eprintln ! ( concat ! ( $ ( stringify ! ( $ a ) , " = {:?}, " ) ,* ) , $ ( $ a ) ,* ) ; } }
#[doc = " https://github.com/hatoo/competitive-rust-snippets"]
const BIG_STACK_SIZE: bool = true;
#[allow(dead_code)]
fn main() {
    use std::thread;
    if BIG_STACK_SIZE {
        thread::Builder::new()
            .stack_size(32 * 1024 * 1024)
            .name("solve".into())
            .spawn(solve)
            .unwrap()
            .join()
            .unwrap();
    } else {
        solve();
    }
}
// O(n logk)
fn calc_mid(a: &[i64], k: usize) -> Vec<i64> {
    let mut res = vec![];
    let mut n = a.len();
    let mut cur = 0;
    let mut aa = vec![];
    // n/k
    while n >= k {
        aa.clear();
        for _ in 0..k {
            aa.push(a[cur]);
            cur += 1;
            n -= 1;
        }
        // klogk
        aa.sort();
        let x = if k%2==0 {
            aa[(k/2)-1]
        } else {
            aa[((k+1)/2)-1]
        };
        res.push(x)
    }
    res
}
fn dp(a: &[i64], k: usize) -> i64 {
    let maxn = a.len() / k;
    // O(n logk)
    let left = calc_mid(&a, k);
    assert!(left.len() == maxn);
    let mut leftcum = CumSum1::new(maxn);
    for i in 0..maxn {
        leftcum.set(i, left[i]);
    }
    leftcum.build();

    // O(n)
    let mut a = a.to_owned(); a.reverse();
    // O(n logk)
    let right = calc_mid(&a, k);
    assert!(right.len() == maxn);
    let mut rightcum = CumSum1::new(maxn);
    for i in 0..maxn {
        rightcum.set(i, right[i]);
    }
    rightcum.build();

    let mut maxv = std::i64::MIN;
    // O((n/k)^2)
    for l in 0..maxn+1 {
        for r in 0..(maxn-l+1) {
            let v = leftcum.query(0, l) + rightcum.query(0, r);
            maxv = max(maxv, k as i64 * v);
        }
    }
    maxv
}
fn solve() {
    input!{
        n: usize,
        a: [i64; n],
    }
    // k=1 (kadane)
    let mut sum = 0;
    let mut b = vec![];
    for i in 0..n {
        sum += a[i];
        b.push(-1 * a[i]); // 逆転
    }
    let maxsub = kadane(&b);
    let mut maxv = 0;

    let mut v = sum;
    if maxsub > 0 {
        v += maxsub;
    }
    maxv = max(maxv, v);

    // k>=2
    // n^2 (1/4+1/9+1/16+...1/n^2)
    // だめそうだがやってみましょう
    for k in 2..n+1 {
        maxv = max(maxv, dp(&a, k));
    }
    println!("{}", maxv);
}
#[doc = "return the sum of the maximum subarray. (Kadane's algorithm). O(N)"]
fn kadane(xs: &[i64]) -> i64 {
    let mut max_ending_here = xs[0];
    let mut max_so_far = xs[0];
    for i in 1..xs.len() {
        let x = xs[i];
        max_ending_here = max(x, max_ending_here + x);
        max_so_far = max(max_so_far, max_ending_here);
    }
    max_so_far
}
struct CumSum1 {
    base: Vec<i64>,
    dp: Vec<i64>,
}
impl CumSum1 {
    fn new(n: usize) -> CumSum1 {
        CumSum1 {
            base: vec![0; n],
            dp: vec![],
        }
    }
    fn add(&mut self, i: usize, x: i64) {
        self.base[i] += x;
    }
    fn set(&mut self, i: usize, x: i64) {
        self.base[i] = x;
    }
    fn build(&mut self) {
        let n = self.base.len();
        let mut dp = vec![0; n + 1];
        let mut acc = 0;
        for i in 0..n {
            acc += self.base[i];
            dp[i + 1] = acc;
        }
        self.dp = dp;
    }
    #[doc = "[i,j)"]
    fn query(&self, i: usize, j: usize) -> i64 {
        self.dp[j] - self.dp[i]
    }
}