#define _USE_MATH_DEFINES
#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
using namespace std;

/*BigInteger
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/rational.hpp>
namespace xxx = boost::multiprecision;
using Bint = xxx::cpp_int;
using Real = xxx::number<mp::cpp_dec_float<1024>>;
*/

#define int long long
#define pb(x) push_back(x)
#define m0(x) memset((x), 0, sizeof(x))
#define mm(x) memset((x), -1, sizeof(x))

//container
#define ALL(x) (x).begin(), (x).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EACH(i, c) for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define UNIQUE(v) (v).erase(unique((v).begin(), (v).end()), (v).end());
#define PERM(c) \
  sort(ALL(c)); \
  for (bool c##p = 1; c##p; c##p = next_permutation(ALL(c)))

// debug
#define GET_VAR_NAME(variable) #variable
#define test(x) cout << GET_VAR_NAME(x) << " = " << x << endl;

// bit_macro
#define bit(n) (1LL << (n))
#define bitset(a, b) (a) |= (1 << (b))
#define bitunset(a, b) (a) &= ~(1 << (b))
#define bitcheck(a, b) ((((a) >> (b)) & 1) == 1)
#define bitcount(a) __builtin_popcountll((a))

//typedef
typedef long long lint;
typedef unsigned long long ull;
typedef complex<long double> Complex;
typedef pair<int, int> P;
typedef tuple<int, int, int> TP;
typedef vector<int> vec;
typedef vector<vec> mat;

//constant
const int INF = (int)1e18;
const int MOD = (int)1e9 + 7;
const double PI = (double)acos(-1);
const double EPS = (double)1e-10;
const int dx[] = {-1, 0, 0, 1, 0, -1, -1, 1, 1};
const int dy[] = {0, -1, 1, 0, 0, 1, -1, 1, -1};

//
template <typename T>
void chmax(T &a, T b) { a = max(a, b); }
template <typename T>
void chmin(T &a, T b) { a = min(a, b); }
//
inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T>
inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}

//
struct Accelerate_Cin {
  Accelerate_Cin() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    cout << fixed << setprecision(20);
  };
};

int N;
vector<long long> A;
vector<long long> sum;

signed main() {
  cin >> N;
  A.resize(N);
  sum.resize(N + 1);
  sum[0] = 0;
  for (int i = 0; i < N; ++i) cin >> A[i], sum[i + 1] = sum[i] + A[i];

  long long res = 1LL << 60;
  for (int i = 0; i <= N; ++i) {
    // P < Q となる最大の切れ目を求める: 二分探索を終えた時の left_low
    int low = 0, high = i;
    while (high - low > 1) {
      int mid = (low + high) / 2;
      if (sum[mid] >= sum[i] - sum[mid])
        high = mid;
      else
        low = mid;
    }
    long long P = sum[low], Q = sum[i] - sum[low];     // 候補1
    long long P2 = sum[high], Q2 = sum[i] - sum[high]; // 候補2
    long long left_min = min(P, Q), left_max = max(P, Q);
    if (abs(P2 - Q2) < abs(P - Q)) left_min = min(P2, Q2), left_max = max(P2, Q2);

    // R < S となる最大の切れ目を求める
    low = i, high = N;
    while (high - low > 1) {
      int mid = (low + high) / 2;
      if (sum[mid] - sum[i] >= sum[N] - sum[mid])
        high = mid;
      else
        low = mid;
    }
    long long R = sum[low] - sum[i], S = sum[N] - sum[low];     // 候補1
    long long R2 = sum[high] - sum[i], S2 = sum[N] - sum[high]; // 候補2
    long long right_min = min(R, S), right_max = max(R, S);
    if (abs(R2 - S2) < abs(R - S)) right_min = min(R2, S2), right_max = max(R2, S2);

    // 真ん中の切れ目が i であるときの暫定解
    long long tmp = max(left_max, right_max) - min(left_min, right_min);
    res = min(res, tmp);
  }
  cout << res << endl;
}


Measured memory_bytes: 3328