#![allow(unused_parens)]
#![allow(unused_imports)]
#![allow(non_upper_case_globals)]
#![allow(non_snake_case)]
#![allow(unused_mut)]
#![allow(unused_variables)]
#![allow(dead_code)]

use itertools::Itertools;
use proconio::input;
use proconio::marker::{Chars, Usize1};

#[allow(unused_macros)]
#[cfg(debug_assertions)]
macro_rules! mydbg {
    //($arg:expr) => (dbg!($arg))
    //($arg:expr) => (println!("{:?}",$arg));
      ($($a:expr),*) => {
          eprintln!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
      }
}
#[cfg(not(debug_assertions))]
macro_rules! mydbg {
    ($($arg:expr),*) => {};
}

macro_rules! echo {
    ($($a:expr),*) => {
          $(println!("{}",$a))*
      }
}

use std::cmp::*;
use std::collections::*;
use std::ops::{Add, Div, Mul, Sub};

#[allow(dead_code)]
static INF_I64: i64 = 92233720368547758;
#[allow(dead_code)]
static INF_I32: i32 = 21474836;
#[allow(dead_code)]
static INF_USIZE: usize = 18446744073709551;
#[allow(dead_code)]
static M_O_D: usize = 1000000007;
#[allow(dead_code)]
static PAI: f64 = 3.1415926535897932;

trait IteratorExt: Iterator {
    fn toVec(self) -> Vec<Self::Item>;
}

impl<T: Iterator> IteratorExt for T {
    fn toVec(self) -> Vec<Self::Item> {
        self.collect()
    }
}

trait CharExt {
    fn toNum(&self) -> usize;
    fn toAlphabetIndex(&self) -> usize;
    fn toNumIndex(&self) -> usize;
}
impl CharExt for char {
    fn toNum(&self) -> usize {
        return *self as usize;
    }
    fn toAlphabetIndex(&self) -> usize {
        return self.toNum() - 'a' as usize;
    }
    fn toNumIndex(&self) -> usize {
        return self.toNum() - '0' as usize;
    }
}

trait VectorExt {
    fn joinToString(&self, s: &str) -> String;
}
impl<T: ToString> VectorExt for Vec<T> {
    fn joinToString(&self, s: &str) -> String {
        return self
            .iter()
            .map(|x| x.to_string())
            .collect::<Vec<_>>()
            .join(s);
    }
}

trait StringExt {
    fn get_reverse(&self) -> String;
}
impl StringExt for String {
    fn get_reverse(&self) -> String {
        self.chars().rev().collect::<String>()
    }
}

trait UsizeExt {
    fn pow(&self, n: usize) -> usize;
}
impl UsizeExt for usize {
    fn pow(&self, n: usize) -> usize {
        return ((*self as u64).pow(n as u32)) as usize;
    }
}

macro_rules ! max { ( $ x : expr ) => ( $ x ) ; ( $ x : expr , $ ( $ xs : expr ) ,+ ) => { { use std :: cmp :: max ; max ( $ x , max ! ( $ ( $ xs ) ,+ ) ) } } ; }
macro_rules ! min { ( $ x : expr ) => ( $ x ) ; ( $ x : expr , $ ( $ xs : expr ) ,+ ) => { { use std :: cmp :: min ; min ( $ x , min ! ( $ ( $ xs ) ,+ ) ) } } ; }

fn calc(A: &Vec<u64>, sum: &Vec<u64>, _l: usize, _r: usize) -> (u64, u64) {
    let mut ret = 1000000000_u64;
    let mut l = _l;
    let mut r = _r;
    let mut a = 0;
    let mut b = 0;
    while r - l > 1 {
        let m = (l + r) / 2;
        a = sum[m] - sum[_l];
        b = sum[_r] - sum[m];
        if a < b {
            l = m;
        } else {
            r = m;
        }
    }
    ret = sum[l] - sum[_l];
    a = sum[l] - sum[_l];
    b = sum[_r] - sum[l];
    ret = max(a, b) - min(a, b);
    let mut a2 = sum[r] - sum[_l];
    let mut b2 = sum[_r] - sum[r];
    let ret2 = max(a2, b2) - min(a2, b2);
    if ret < ret2 {
        return (a, b);
    } else {
        return (a2, b2);
    }
}
fn main() {
    use itertools_num::*;
    input! {
       N: usize,
       A:[u64;N],
    }

    let mut ans: u64 = 10000000000;
    let mut sum = std::iter::once(&0).chain(&A).cumsum().collect::<Vec<u64>>();
    for i in 2..N - 1 {
        let (P, Q) = calc(&A, &sum, 0, i);
        let (R, S) = calc(&A, &sum, i, N);
        ans = min(ans, max!(P, Q, R, S) - min!(P, Q, R, S));
    }

    echo!(ans);
}


Measured memory_bytes: 6560