#include <bits/stdc++.h>

#define FOR(i,a,b) for(int i= (a); i<((int)b); ++i)
#define RFOR(i,a) for(int i=(a); i >= 0; --i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

typedef long long LL;
template<typename T> using V = std::vector<T>;
template<typename T> using VV = std::vector<std::vector<T>>;
template<typename T> using VVV = std::vector<std::vector<std::vector<T>>>;

template<class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
template<class T> inline void print(T x) { std::cout << x << std::endl; }
template<class T> inline void print_vec(const std::vector<T> &v) { for (int i = 0; i < v.size(); ++i) {  if (i != 0) {std::cout << " ";} std::cout << v[i];} std::cout << "\n"; }
template<class T> inline bool inside(T y, T x, T H, T W) {return 0 <= y and y < H and 0 <= x and x < W; }
template<class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) { return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); }
template<class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) { return abs(x1 - x2) + abs(y1 - y2); }

const int INF = 1L << 30;
const double EPS = 1e-9;
const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy4 = { 0, 1, 0, -1 }, dx4 = { 1, 0, -1, 0 };    // 4近傍（右, 下, 左, 上）
const std::vector<int> dy8 = { 0, -1, 0, 1, 1, -1, -1, 1 }, dx8 = { 1, 0, -1, 0, 1, 1, -1, -1 };

using namespace std;

class CumulativeSum {

public:
    std::vector<long long> memo1;               // 1次元用の累積和表

    CumulativeSum() {}

    void build(const std::vector<long long> &line) {
        this->memo1.assign(line.size() + 1, 0);

        for (long long i = 0; i < line.size(); ++i) {
            this->memo1[i + 1] = this->memo1[i] + line[i];
        }
    }

    long long sum(int left, int right) {
        return this->memo1[right] - this->memo1[left];
    }
};


pair<LL, LL> func(int left, int right, CumulativeSum &cs) {

    LL total = cs.sum(left, right);

    // [low, high)
    long long low = left, high = right;
    while (high - low > 1) {
        long long middle = (low + high) / 2;
        LL l = cs.sum(left, middle);
        LL r = total - l;
        if (l < r) {
            low = middle;
        }
        else {
            high = middle;
        }
    }

    pair<LL, LL> ans;
    LL best_diff = INF;
    FOR(i, max(0LL, low - 1), min<LL>(right, low + 2)) {
        LL l = cs.sum(left, i);
        LL r = total - l;
        if (abs(l - r) < best_diff) {
            best_diff = abs(l - r);
            ans = make_pair(l, r);
        }
    }

    return ans;
};


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int N;
    cin >> N;
    vector<LL> A(N);
    FOR(i, 0, N) {
        cin >> A[i];
    }

    CumulativeSum cs;
    cs.build(A);

    LL ans = INF;
    FOR(m, 2, N - 1) {
        auto a = func(0, m, cs);
        auto b = func(m, N, cs);

        vector<LL> v = {a.first, a.second, b.first, b.second};
        ans = min(ans, MAX(v) - MIN(v));
    }
    print(ans);

    return 0;
}


Measured memory_bytes: 3456