#include "bits/stdc++.h"
// Begin Header {{{
#define all(x)          (x).begin(), (x).end()
#define rep(i, n)       for (i64 i = 0, i##_limit = (n); i < i##_limit; ++i)
#define reps(i, s, t)   for (i64 i = (s), i##_limit = (t); i <= i##_limit; ++i)
#define repr(i, s, t)   for (i64 i = (s), i##_limit = (t); i >= i##_limit; --i)
#define var(Type, ...)  Type __VA_ARGS__; input(__VA_ARGS__)
#ifndef DBG
#define trace(...)
#endif
using namespace std;
using i64 = int_fast64_t;
using pii = pair<i64, i64>;
template <class T, class U> inline bool chmax(T &a, const U &b) { return b > a && (a = b, true); }
template <class T, class U> inline bool chmin(T &a, const U &b) { return b < a && (a = b, true); }
inline i64  sigma(i64 n)            { return (n * (n + 1) >> 1); }
inline i64  updiv(i64 a, i64 b)     { return (a + b - 1) / b; }
inline i64  sqr(i64 n)              { return n * n; }
inline string to_string(char c)     { return string(1, c); }
constexpr int INF  = 0x3f3f3f3f;
constexpr i64 LINF = 0x3f3f3f3f3f3f3f3fLL;

template <class T>
inline vector<T> make_v(const T &initValue, size_t sz) {
    return vector<T>(sz, initValue);
}
template <class T, class... Args>
inline auto make_v(const T &initValue, size_t sz, Args... args) {
    return vector<decltype(make_v<T>(initValue, args...))>(sz, make_v<T>(initValue, args...));
}

inline void input() {}
template <class Head, class... Tail>
inline void input(Head &head, Tail&... tail) { cin >> head; input(tail...); }

inline void print() { cout << "\n"; }
template <class Head, class... Tail>
inline void print(Head &&head, Tail&&... tail) {
    cout << head;
    if (sizeof...(tail)) cout << ' ';
    print(forward<Tail>(tail)...);
}

template <class T>
inline ostream& operator<< (ostream &out, const vector<T> &vec) {
    static constexpr const char *delim[] = { " ", "" };
    for (const auto &e : vec) out << e << delim[&e == &vec.back()];
    return out;
}

template <typename Func>
struct FixPoint : Func {
    inline constexpr FixPoint(Func &&f) noexcept : Func(forward<Func>(f)) {}

    template <typename... Args>
    inline decltype(auto) operator()(Args &&... args) const {
        return Func::operator()(*this, forward<Args>(args)...);
    }
};

template< typename Func >
inline decltype(auto) makeFixPoint(Func &&f) {
    return FixPoint< Func >{forward< Func >(f)};
}
// }}} End Header

class CumulativeSum { // {{{{
    vector<i64> cum;

public:
    CumulativeSum() : cum(1) {}

    CumulativeSum(int sz) : cum(sz + 1) {}

    template<class T>
        CumulativeSum(initializer_list<T> il) { assign(il.begin(), il.end()); }

    template<class Iterator>
        CumulativeSum(Iterator begin, Iterator end) { assign(begin, end); }

    template<class Iterator>
        inline void assign(Iterator begin, Iterator end) {
            cum.assign(distance(begin, end) + 1, 0);
            std::copy(begin, end, cum.begin() + 1);
        }

    inline void build() {
        for (int i = 1; i < cum.size(); ++i) {
            cum[i] += cum[i-1];
        }
    }

    // "半開区間" [0, r) までの総和
    inline i64 sum(int r) const {
        return cum[r];
    }

    // "半開区間" [l, r) までの総和
    inline i64 sum(int l, int r) const {
        return sum(r) - sum(l);
    }

    ///////////////////////////////////////////////////////////////////////////
    // vector like methods
    inline void resize(int sz) {
        cum.resize(sz + 1);
    }
    template<class... Args>
        inline void emplace_back(Args&&... args) {
            cum.emplace_back(args...);
        }
    inline i64 size() const noexcept {
        return static_cast<i64>(cum.size()) - 1;
    }
    inline const auto& data() const noexcept {
        return cum;
    }
    inline auto begin() const noexcept {
        return cum.begin() + 1;
    }
    inline auto end() const noexcept {
        return cum.end();
    }
    inline i64 operator[](int i) const {
        return cum[i + 1];
    }
    inline i64& operator[](int i) {
        return cum[i + 1];
    }
};
// }}}

signed main()
{
    ios::sync_with_stdio(false); cin.tie(nullptr);

    var(int, N);
    CumulativeSum cum(N);

    rep(i, N) {
        input(cum[i]);
    }

    cum.build();

    const auto f = [&](int l, int m, int r) {
        if (l <= 0 || m <= l || r <= m || N <= r) return LINF;
        const i64 P = cum.sum(0, l);
        const i64 Q = cum.sum(l, m);
        const i64 R = cum.sum(m, r);
        const i64 S = cum.sum(r, N);
        return max(max(max(P, Q), R), S) - min(min(min(P, Q), R), S);
    };

    i64 ans = LINF;
    reps(mid, 2, N-1) {
        const int l = lower_bound(all(cum), cum.sum(0, mid) / 2) - cum.begin();
        const int r = lower_bound(all(cum), cum.sum(0, mid) + cum.sum(mid, N) / 2) - cum.begin();
        reps(addL, -2, 2) reps(addR, -2, 2) {
            chmin(ans, f(l + addL, mid, r + addR));
        }
    }

    print(ans);

    return 0;
}


Measured memory_bytes: 1792