#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <cctype>
#include <climits>
#include <string>
#include <bitset>
#include <cfloat>
#include <unordered_set>
#pragma GCC optimize("Ofast")
using namespace std;
typedef long double ld;
typedef long long int ll;
typedef unsigned long long int ull;
typedef vector<int> vi;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef vector<string> vs;
typedef vector<ll> vll;
typedef vector<pair<int,int> > vpii;
typedef vector<vector<int> > vvi;
typedef vector<vector<char> > vvc;
typedef vector<vector<string> > vvs;
typedef vector<vector<ll> > vvll;
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define irep(it, stl) for(auto it = stl.begin(); it != stl.end(); it++)
#define drep(i,n) for(int i = (n) - 1; i >= 0; --i)
#define fin(ans) cout << (ans) << '\n'
#define STI(s) atoi(s.c_str())
#define mp(p,q) make_pair(p, q)
#define pb(n) push_back(n)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define Sort(a) sort(a.begin(), a.end())
#define Rort(a) sort(a.rbegin(), a.rend())
#define MATHPI acos(-1)
#define itn int;
int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};
template <class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;} return 0;}
template <class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;} return 0;}
struct io{io(){ios::sync_with_stdio(false);cin.tie(0);}};
const int INF = INT_MAX;
const ll LLINF = 1LL<<60;
const ll MOD = 1000000007;
const double EPS = 1e-9;

class Monoid {
public:
    // 単位元
    ll unit;
    
    Monoid() {
        // 単位元
        unit = 0;
    }

    // 演算関数
    ll calc(ll a, ll b) {
        return a + b; 
    }
};

class SegmentTree {
public:
    // セグメント木の葉の要素数
    ll n;

    // セグメント木
    vector<ll> tree;

    // モノイド
    Monoid mono;

    SegmentTree(vector<ll> &v) {
        n = 1 << (ll)ceil(log2(v.size()));
        tree = vector<ll>(n << 1);
        for(ll i = 0; i < v.size(); i++) {
            update(i, v[i]);
        }
        for(ll i = v.size(); i < n; i++) {
            update(i, mono.unit);
        }
    }

    // k番目の値(0-indexed)をxに変更
    void update(ll k, ll x) {
        k += n;
        tree[k] = x;
        for(k = k >> 1; k > 0; k >>= 1){
            tree[k] = mono.calc(tree[k << 1 | 0], tree[k << 1 | 1]);
        }
    }

    // [l, r)の最小値(0-indexed)を求める．
    ll query(ll l, ll r) {
        ll res = mono.unit;
        l += n;
        r += n;
        while(l < r) {
            if(l & 1) {
                res = mono.calc(res, tree[l++]);
            }
            if(r & 1) {
                res = mono.calc(res, tree[--r]);
            }
            l >>= 1;
            r >>= 1;
        }
        return res;
    }
};

pair<ll,ll> binarysearch(int l, int r, ll s, ll t, SegmentTree &st) {
    int ok = l - 1; //これがx以下 
    int ng = r + 1; //x以上
    // 問題によってokとngを入れ替える
    for(int j = 0; j < 18; j++) {
        int mid = (ok + ng)/2;
        ll nowdiff = abs(s - t);
        ll lsum = st.query(l, mid + 1);
        ll rsum = st.query(mid + 1, r + 1);
        ll nextdiff = abs(lsum - rsum);
        if(nowdiff > nextdiff){
            s = lsum;
            t = rsum;
        }
        if(lsum < rsum) {
            ok = mid;
        }
        else ng = mid;
    }
    return mp(s, t);
}

int main(void) {
    
    int n;
    scanf("%d", &n);
    vll a(n);
    rep(i,n){
        scanf("%lld", &a[i]);
    }
    SegmentTree st(a);
    ll ans=LLINF;
    for(int i = 1; i < n - 2; ++i) { //どこで切るか
        ll s=0,t=LLINF,u=0,v=LLINF;
        auto p1 = binarysearch(0, i, s, t, st);
        auto p2 = binarysearch(i + 1, n - 1, u, v, st);
        s = p1.first; t = p1.second; u = p2.first; v = p2.second;
        chmin(ans, max(max(s, t), max(u, v)) - min(min(s, t), min(u, v)));
    }
    printf("%lld\n", ans);
}

Measured memory_bytes: 5888