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

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pullull;
typedef pair<ll, int> plli;
typedef pair<int, pii> pipii;
typedef vector<vector<int> > mati;
typedef vector<vector<double> > matd;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;
typedef vector<bool> vb;
typedef vector<vector<bool>> vvb;
typedef vector<vector<vector<bool>>> vvvb;
typedef vector<pll> vpll;
typedef vector<vpll> vvpll;

#define FOR(i,x,y) for(ll i=(ll)x; i<(ll)y; ++i)
#define REP(i,y) FOR(i, 0, y)
#define RFOR(i,x,y) for(ll i=(ll)x; i>=(ll)y; --i)
#define RREP(i,x) RFOR(i, x, 0)
#define ALL(a) a.begin(), a.end()
#define pb push_back
#define debug_printf(x...) cerr << "line " << __LINE__ << " : "; debug_printf_in(x);

template <typename First>
void debug_printf_in(First first){
  cerr << first << endl;
  return;
}

template <typename First, typename... Rest>
void debug_printf_in(First first, Rest... rest){
  cerr << first << " ";
  debug_printf_in(rest...);
  return;
}

void IN(void){
  return;
}

template <typename First, typename... Rest>
void IN(First& first, Rest&... rest){
  cin >> first;
  IN(rest...);
  return;
}

template <typename First>
void OUT(First first){
  cout << first << endl;
  return;
}

template <typename First, typename... Rest>
void OUT(First first, Rest... rest){
  cout << first << " ";
  OUT(rest...);
  return;
}

template<class t, class u> void chmax(t&a,u b){if(a<b)a=b;};
template<class t, class u> void chmin(t&a,u b){if(a>b)a=b;};
int popcount(int t){return __builtin_popcount(t);} //GCC
int popcount(ll t){return __builtin_popcountll(t);} //GCC

template <typename T>
void vec_print(vector<T> VEC){
  REP(i, VEC.size()){
    cout << VEC[i] << " ";
  }
  cout << "\n";
};

template <typename T>
void mat_print(vector<vector<T> > MAT){
  REP(i, MAT.size()){
    REP(j, MAT[i].size()){
      cout << MAT[i][j] << " ";
    }
    cout << "\n";
  }
};

template <typename CLASS1, typename CLASS2>
class HOGE{
  public:
    CLASS1 key;
    CLASS2 value;
    HOGE(void){
      return;
    };
    HOGE(CLASS1 key, CLASS2 value){
      this->key = key;
      this->value = value;
    };
    ~HOGE(void){
      return;
    };

    void print(void){
      cout << "key : " << key << ", value : " << value << "\n";
      return;
    };
    
    bool operator==(const HOGE &obj){
      return (this->value == obj.value);
    };
    bool operator<(const HOGE &obj){
      return (this->value < obj.value);
    };
    bool operator>(const HOGE &obj){
      return (this->value > obj.value);
    };
};

template <typename CLASS1, typename CLASS2>
bool operator==(const HOGE<CLASS1, CLASS2> &hoge1, const HOGE<CLASS1, CLASS2> &hoge2){
  return hoge1.value == hoge2.value;
};

template <typename CLASS1, typename CLASS2>
bool operator<(const HOGE<CLASS1, CLASS2> &hoge1, const HOGE<CLASS1, CLASS2> &hoge2){
  return hoge1.value < hoge2.value;
};

template <typename CLASS1, typename CLASS2>
bool operator>(const HOGE<CLASS1, CLASS2> &hoge1, const HOGE<CLASS1, CLASS2> &hoge2){
  return hoge1.value > hoge2.value;
};

constexpr int INF = (1<<30);
constexpr ll INFLL = 1LL<<62;
constexpr long double EPS = 1e-12;
constexpr ll MOD = (ll)((1E+9)+7);

int main(){
  cin.tie(0); // cut the cin and cout (default, std::flush is performed after std::cin)
  ios::sync_with_stdio(false); // cut the iostream and stdio (DON'T endl; BUT "\n";)

  ll N;
  IN(N);
  vll A(N);
  REP(i,N) IN(A[i]);
  vpll dp1(N);
  vpll dp2(N);

  dp1[0] = make_pair(0, A[0]);
  ll tail = 0;
  FOR(i,1,N){
    dp1[i] = dp1[i-1];
    dp1[i].second += A[i];
    while(abs(dp1[i].first-dp1[i].second)>=abs(dp1[i].first-dp1[i].second+2*A[tail])){
      dp1[i].first += A[tail];
      dp1[i].second -= A[tail];
      ++tail;
      if(tail>i) break;
    }
    //debug_printf(i, tail, dp1[i].first, dp1[i].second);
  }

  /*
  REP(i,N){
    printf("%lld : %lld %lld\n", i, dp1[i].first, dp1[i].second);
  }
  */

  dp2[N-1] = make_pair(A[N-1], 0);
  tail = N-1;
  RREP(i,N-2){
    dp2[i] = dp2[i+1];
    dp2[i].first += A[i];
    while(abs(dp2[i].first-dp2[i].second)>=abs(dp2[i].first-dp2[i].second-2*A[tail])){
      dp2[i].first -= A[tail];
      dp2[i].second += A[tail];
      --tail;
      if(tail<i) break;
    }
    //debug_printf(i, tail, dp2[i].first, dp2[i].second);
  }

  /*
  REP(i,N){
    printf("%lld : %lld %lld\n", i, dp1[i].first, dp1[i].second);
  }
  REP(i,N){
    printf("%lld : %lld %lld\n", i, dp2[i].first, dp2[i].second);
  }
  */

  ll ans = INFLL;
  vll tmp(4);
  FOR(i,1,N-1){
    tmp[0] = dp1[i].first;
    tmp[1] = dp1[i].second;
    tmp[2] = dp2[i+1].first;
    tmp[3] = dp2[i+1].second;
    ll tmpmax = max({tmp[0], tmp[1], tmp[2], tmp[3]});
    ll tmpmin = min({tmp[0], tmp[1], tmp[2], tmp[3]});
    chmin(ans, tmpmax-tmpmin);
  }

  OUT(ans);

  return 0;
}

Measured memory_bytes: 8064