#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using VI = vector<ll>;
using VV = vector<VI>;
using VS = vector<string>;

// tourist set
template <typename A, typename B>
string to_string(pair<A, B> p);

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);

string to_string(const string& s) {
  return '"' + s + '"';
}

string to_string(const char* s) {
  return to_string((string) s);
}

string to_string(bool b) {
  return (b ? "true" : "false");
}

string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}";
  return res;
}

template <size_t N>
string to_string(bitset<N> v) {
  string res = "";
  for (size_t i = 0; i < N; i++) {
    res += static_cast<char>('0' + v[i]);
  }
  return res;
}

template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}

template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}

void debug_out() { cerr << '\n'; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
// tourist set end

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define rep(i,b) FOR(i, 0, b)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<'\n'
#define p2(s, t) cout << (s) << " " << (t) << '\n'
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << '\n'
#define p_yes() p("YES")
#define p_no() p("NO")
#define SZ(x) ((int)(x).size())
#define SORT(A) sort(ALL(A))
#define RSORT(A) sort(ALL(A), greater<ll>())

void no(){p_no(); exit(0);}
void yes(){p_yes(); exit(0);}

const ll mod = 1e9 + 7;
const ll inf = 1e18;
const double PI = acos(-1);

struct AccSum{
    vector<ll> Ac;
    ll L;
    AccSum(vector<ll> &A){
        L = A.size();
        Ac.resize(L+1);
        FOR(i, 0, L){
            Ac[i+1] = Ac[i] + A[i];
        }
    }
    // sum of [a, b]
    ll sum(ll a, ll b){
        if(a<0) return -1;
        if(b>L-1) return -1;
        return Ac[b+1] - Ac[a];
    }
};

ll f(ll a, ll b, ll c, ll d){
  VI V;
  V.push_back(a);
  V.push_back(b);
  V.push_back(c);
  V.push_back(d);
  SORT(V);
  return V[3] - V[0];
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll N; 
    cin >> N;

    VI A(N);
    rep(i, N){
        cin >> A.at(i);
    }

    AccSum Acc(A);

    ll a = A[0];
    ll b = A[1];
    ll left_cut = 0;
    ll right_cut = 2;
    {
      ll min_diff = abs(A[2] - Acc.sum(3, N-1));
      FOR(i, 3, N-1){
        ll left = Acc.sum(2, i);
        ll right = Acc.sum(i+1, N-1);
        ll diff = abs(left-right);
        if(diff<min_diff){
          right_cut = i;
          min_diff = diff;
        }
      }
    }
    debug(right_cut);
    ll c = Acc.sum(2, right_cut);
    ll d = Acc.sum(right_cut+1, N-1);
    ll mi = f(a, b, c, d);
    debug(a,b,c,d);
    debug(mi);

    // 中央カット位置
    FOR(cut, 2, N-2){
      while(1){
        // 今の左右の差
        ll a = Acc.sum(0, left_cut);
        ll b = Acc.sum(left_cut+1, cut);

        // 一歩進めた左右の差
        ll a2 = Acc.sum(0, left_cut+1);
        ll b2 = Acc.sum(left_cut+2, cut);
 
        if(abs(a-b) >= abs(a2-b2)){
          left_cut++;
        }else{
          break;
        }
      }

      while(1){
        ll c = Acc.sum(cut+1, right_cut);
        ll d = Acc.sum(right_cut+1, N-1);

        ll c2 = Acc.sum(cut+1, right_cut+1);
        ll d2 = Acc.sum(right_cut+2, N-1);

        if(abs(c-d) >= abs(c2-d2)){
          right_cut++;
        }else{
          break;
        }
      }


      debug(cut, left_cut, right_cut);

      ll a = Acc.sum(0, left_cut);
      ll b = Acc.sum(left_cut+1, cut);
      ll c = Acc.sum(cut+1, right_cut);
      ll d = Acc.sum(right_cut+1, N-1);
      chmin(mi, f(a,b,c,d));
    }
    p(mi);
    
    return 0;
}

Measured memory_bytes: 3328