#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <algorithm>
#include <cmath>
#include <string>
#include <cstring>
#include <map>
#include <set>
#include <bitset>
#include <sstream>
#include <cstdlib>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <random>
#include <functional>
#include <climits>
#include <cstdio>
#include <ctype.h>
#include <time.h>
using namespace std;

#define PI acos(-1.0)
#define EPS 1e-8
#define MOD 1000000007
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define pb push_back
#define fi first
#define se second
#define go(i, a, b) for(int i = a; i <= b; ++i)
#define gorev(i, a, b) for(int i = a; i >= b; --i)

typedef long double ld;
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;

template <class L, class R> ostream &operator <<(ostream &os, pair<L, R> P){
    return os << "(" << P.fi << "," << P.se << ")";
}
template <class T> ostream &operator <<(ostream &os, vector<T> V){
    os << "["; for (auto vv: V) os << vv << ","; return os << "]";
}
template <class L, class R> ostream &operator <<(ostream &os, map<L, R> M){
    os << "["; for (auto pr: M) os << pr.fi << "->" << pr.se << ","; return os << "]";
}
template <class L, class R> ostream &operator <<(ostream &os, unordered_map<L, R> M){
    os << "["; for (auto pr: M) os << pr.fi << "->" << pr.se << ","; return os << "]";
}

mt19937_64 mt(time(0));

struct Matrix {
    vvi data;
    int r, c;
    Matrix(int row, int col, bool identity = false) : r(row), c(col) {
        data.assign(row, vector<int>(col, 0));
        if (identity) {
            for (int i = 0; i < r; ++i) {
                data[i][i] = 1;
            }
        }
    }
    Matrix operator * (Matrix& other) {
        int m = r, n = c, p = other.c;
        Matrix res(m, p);
        for (int i = 0; i < m; ++i) {
            for (int j = 0; j < p; ++j) {
                for (int k = 0; k < n; ++k) {
                    res.data[i][j] += data[i][k] * other.data[k][j];
                }
            }
        }
        return res;
    }
};

vector<int> extendGcd(int a, int b) {
    if (b == 0) {
        return {1, 0, a};
    } else {
        vector<int> tmp = extendGcd(b, a % b);
        return {tmp[1], tmp[0] - (a / b) * tmp[1], tmp[2]};
    }
}

Matrix matrix_power(Matrix base, ll exp) {
    int n = base.r;
    Matrix res(n, n, true);
    while (exp) {
        if (exp & 1) {
            res = res * base;
        }
        base = base * base;
        exp >>= 1;
    }
    return res;
}

inline char get(void) {
    static char buf[100000], *S = buf, *T = buf;
    if (S == T) {
        T = (S = buf) + fread(buf, 1, 100000, stdin);
        if (S == T) return EOF;
    }
    return *S++;
}

template<class T> inline void read(T &x) {
    static char c; x = 0; int sgn = 0;
    for (c = get(); c < '0' || c > '9'; c = get()) if (c == '-') sgn = 1;
    for (; c >= '0' && c <= '9'; c = get()) x = x * 10 + c - '0';
    if (sgn) x = -x;
}

/*************************
 ******* template ********
 ************************/

#define N 200010
int n;
ll a[N], pre[N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cout.precision(10);
    cout << fixed;
#ifdef ZYC_LOCAL
    freopen("input.txt", "rt", stdin);
#endif
    cin >> n;
    go(i, 1, n) {
        cin >> a[i];
        pre[i] = a[i] + pre[i - 1];
    }

    ll res = LLONG_MAX;
    go(k, 2, n - 2) {
        int i, j;
        int l = 1, r = k - 1;
        while (l < r) {
            int mid = r - (r - l) / 2;
            if (pre[mid] <= pre[k] - pre[mid]) {
                l = mid;
            } else {
                r = mid - 1;
            }
        }
        i = l;
        l = k + 1, r = n - 1;
        while (l < r) {
            int mid = r - (r - l) / 2;
            if (pre[mid] - pre[k] <= pre[n] - pre[mid]) {
                l = mid;
            } else {
                r = mid - 1;
            }
        }
        j = l;
        for (int ii = i; ii <= min(i + 1, k - 1); ++ii) {
            for (int jj = j; jj <= min(j + 1, n - 1); ++jj) {
                ll s[4];
                s[0] = pre[ii];
                s[1] = pre[k] - pre[ii];
                s[2] = pre[jj] - pre[k];
                s[3] = pre[n] - pre[jj];
                sort(s, s + 4);
                res = min(res, s[3] - s[0]);
            }
        }
    }
    cout << res;

#ifdef ZYC_LOCAL
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
    return 0;
}


Measured memory_bytes: 3456