#include <bits/stdc++.h>

template <typename T>
T BinarySearch(T ok, T ng, std::function<bool(T)> pred) {
  if constexpr (std::is_integral<T>::value) {
    while ((ok > ng ? ok - ng : ng - ok) > 1) {
      T mid = ok + (ng - ok) / 2;
      (pred(mid) ? ok : ng) = mid;
    }
    return ok;
  }
  if constexpr (std::is_floating_point<T>::value) {
    for (int i = 0; i < 200; ++i) {
      T mid = (ok + ng) / 2;
      (pred(mid) ? ok : ng) = mid;
    }
    return ok;
  }
}

template <typename T, typename = void>
struct is_iterable : std::false_type {};
template <typename T>
struct is_iterable<T, std::void_t<decltype(std::begin(std::declval<T>())),
                                  decltype(std::end(std::declval<T>()))>>
    : std::true_type {};

template <typename T, typename = void>
struct is_pair : std::false_type {};
template <typename T>
struct is_pair<T, std::void_t<decltype(std::declval<T>().first),
                              decltype(std::declval<T>().second)>>
    : std::true_type {};

template <typename T>
void debug(const T& v) {
  if constexpr (is_pair<T>::value) {
    std::cerr << "{";
    debug(v.first);
    std::cerr << ", ";
    debug(v.second);
    std::cerr << "}";
  } else if constexpr (is_iterable<T>::value &&
                       !std::is_same<T, std::string>::value) {
    std::cerr << "{";
    for (auto it = v.begin(); it != v.end(); ++it) {
      if (it != v.begin()) std::cerr << ", ";
      debug(*it);
    }
    std::cerr << "}";
  } else {
    std::cerr << v;
  }
}
template <typename T, typename... Ts>
void debug(const T& value, const Ts&... args) {
  debug(value);
  std::cerr << ", ";
  debug(args...);
}
#if DEBUG
#define dbg(...)                        \
  do {                                  \
    cerr << #__VA_ARGS__ << ": ";       \
    debug(__VA_ARGS__);                 \
    cerr << " (L" << __LINE__ << ")\n"; \
  } while (0)
#else
#define dbg(...)
#endif

void read_from_cin() {}
template <typename T, typename... Ts>
void read_from_cin(T& value, Ts&... args) {
  std::cin >> value;
  read_from_cin(args...);
}
#define rd(type, ...) \
  type __VA_ARGS__;   \
  read_from_cin(__VA_ARGS__);
#define ints(...) rd(int, __VA_ARGS__);
#define strings(...) rd(string, __VA_ARGS__);

template <typename T>
void write_to_cout(const T& value) {
  if constexpr (std::is_same<T, bool>::value) {
    std::cout << (value ? "Yes" : "No");
  } else {
    std::cout << value;
  }
}
template <typename T, typename... Ts>
void write_to_cout(const T& value, const Ts&... args) {
  write_to_cout(value);
  std::cout << ' ';
  write_to_cout(args...);
}
#define wt(...)                 \
  do {                          \
    write_to_cout(__VA_ARGS__); \
    cout << '\n';               \
  } while (0)

#define all(x) (x).begin(), (x).end()

#define rep_dispatch(_1, _2, _3, name, ...) name
#define rep3(i, a, b) for (int i = (a); i < (b); ++i)
#define rep2(i, n) rep3(i, 0, n)
#define rep1(n) rep2(_loop_variable_, n)
#define rep(...) rep_dispatch(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__)

#define rrep(i, n) for (int i = (int)(n)-1; i >= 0; --i)

template <typename T>
std::istream& operator>>(std::istream& is, std::vector<T>& v) {
  for (T& vi : v) is >> vi;
  return is;
}

template <typename T, typename U>
bool chmax(T& a, U b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

template <typename T, typename U>
bool chmin(T& a, U b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

template <typename T>
int sz(const T& v) {
  return v.size();
}

#include <boost/hana/functional/fix.hpp>
const auto& Fix = boost::hana::fix;

using ll = long long;

template <typename T>
using low_priority_queue =
    std::priority_queue<T, std::vector<T>, std::greater<T>>;

template <typename T>
using V = std::vector<T>;
template <typename T>
using VV = V<V<T>>;

using namespace std;

int main() {
#define int ll
  ints(n);
  V<int> a(n);
  cin >> a;

  V<int> l(n);
  rep(i, n) l[i] = a[i] + (i > 0 ? l[i - 1] : 0);
  V<int> r(n);
  rrep(i, n) r[i] = a[i] + (i < n - 1 ? r[i + 1] : 0);

  // int all = accumulate(all(a), 0LL);

  int ans = numeric_limits<int>::max();
  rep(i, 1, n - 2) {
    int ls = l[i];
    int li = BinarySearch<int>(0, i, [&](int i) { return l[i] <= ls / 2; });
    int rs = r[i + 1];
    int ri =
        BinarySearch<int>(n - 1, i + 1, [&](int i) { return r[i] <= rs / 2; });
    dbg(i, li, ls, l[li]);
    dbg(i + 1, ri, rs, r[ri]);
    rep(ld, -1, 2) rep(rd, -1, 2) {
      int lid = li + ld, rid = ri + rd;
      dbg(lid, rid);
      if (lid < 0 || i <= lid || rid <= i + 1 || n - 1 < rid) continue;
      int l1 = l[lid], l2 = ls - l1;
      int r1 = r[rid], r2 = rs - r1;
      chmin(ans, max({l1, l2, r1, r2}) - min({l1, l2, r1, r2}));
    }
    // dbg(i, ls, rs, all);
    // assert(ls + rs == all);
  }
  wt(ans);
}


Measured memory_bytes: 8012