#include <bits/stdc++.h>
using namespace std;
#define int long long
#define stoi stoll
using ll=long long;
using vi=vector<int>;
using pii=pair<int,int>;
#define ALL(c) begin(c),end(c)
#define RALL(c) rbegin(c),rend(c)
#define ITR(i,b,e) for(auto i=(b);i!=(e);++i)
#define FORE(x,c) for(auto &x:c)
#define REPF(i,a,n) for(int i=a,i##len=(int)(n);i<i##len;++i)
#define REP(i,n) REPF(i,0,n)
#define REPR(i,n) for(int i=(int)(n);i>=0;--i)
#define SZ(c) ((int)c.size())
#define CONTAIN(c,x) (c.find(x)!=end(c))
#define INSEG(l,x,r) ((l)<=(x)&&(x)<(r))
#define dump(...)
#define pb push_back
#define _ 0
const signed INF_=1001001001; const long long INF=1001001001001001001LL;
const int DX[9]={0,1,0,-1,1,1,-1,-1,0},DY[9]={-1,0,1,0,-1,1,1,-1,0};
template<class T> ostream& operator<<(ostream &os,const vector<T> &v) {
    ITR(i,begin(v),end(v))os<<*i<<(i==end(v)-1?"":" ");return os;}
template<class T> istream& operator>>(istream &is,vector<T> &v) {
    ITR(i,begin(v),end(v)) is>>*i;return is;}
template<class T,class U> istream& operator>>(istream &is, pair<T,U> &p) {
    is>>p.first>>p.second;return is;}
template<class T, class U> bool chmax(T &a,const U &b){return a<b?a=b,1:0;}
template<class T, class U> bool chmin(T &a,const U &b){return a>b?a=b,1:0;}
template<class T> using heap=priority_queue<T,vector<T>,greater<T>>;
struct before_main_function {
    before_main_function() {
        cin.tie(0); ios::sync_with_stdio(false);
        cout << setprecision(15) << fixed;
        #define endl "\n"
    }
} before_main_function;
//------------------8<------------------------------------8<--------------------

signed main() {
    int N;
    cin >> N;
    vi A(N);
    cin >> A;
    vi S(N);
    S[0] = A[0];
    REPF(i, 1, N) S[i] = S[i - 1] + A[i];
    // [l, r)
    auto sum = [&](int l, int r) {
        return S[r - 1] - (l > 0 ? S[l - 1] : 0);
    };
    
    int ans = INF;
    REPF(i, 2, N - 1) {
        bool valid = true;
        int a, b;
        {
            int L = 0, R = i;
            while (R - L > 1) {
                int M = (L + R) / 2;
                valid &= (1 <= M && M <= i - 1);
                if (sum(0, M) <= sum(M, i)) L = M;
                else R = M;
            }

            int P1 = sum(0, L), Q1 = sum(L, i), P2 = sum(0, L + 1), Q2 = sum(L + 1, i);
            if (L < 1) {
                a = P2, b = Q2;
            } else if (L + 1 >= i) {
                a = P1, b = Q1;
            } else if (abs(Q1 - P1) < abs(P2 - Q2)) {
                a = P1, b = Q1;
            } else {
                a = P2, b = Q2;
            }
        }
        int c, d;
        {
            int L = i, R = N;
            while (R - L > 1) {
                int M = (L + R) / 2;
                valid &= (i + 1 <= M && M <= N - 1);
                if (sum(i, M) <= sum(M, N)) L = M;
                else R = M;
            }

            int R1 = sum(i, L), S1 = sum(L, N), R2 = sum(i, L + 1), S2 = sum(L + 1, N);
            if (L < i + 1) {
                c = S2, d = R2;
            } else if (L + 1 >= N) {
                c = S1; d = R1;
            } else if (abs(S1 - R1) < abs(R2 - S2)) {
                c = S1; d = R1;
            } else {
                c = S2, d = R2;
            }
        }
        if (!valid) continue;
        chmin(ans, max({a, b, c, d}) - min({a, b, c, d}));
    }
    cout << ans << endl;
    return (0^_^0);
}



Measured memory_bytes: 3328