// g++ macro.cpp -std=c++14
#include <bits/stdc++.h>
typedef long long ll;
const int INF = 1e9;
const int MOD = 1e9+7;
const ll LINF = 1e18;
using namespace std;
 
#define dump(x)  cout << #x << " = " << (x) << endl;
#define YES(n) cout << ((n) ? "YES" : "NO"  ) << endl
#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl
#define POSSIBLE(n) cout << ((n) ? "POSSIBLE" : "IMPOSSIBLE"  ) << endl
#define Possible(n) cout << ((n) ? "Possible" : "Impossible"  ) << endl
#define possible(n) cout << ((n) ? "possible" : "impossible"  ) << endl
 
#define SANKOU(n,a,b) cout << ((n) ? (#a) : (#b) ) << endl
 
#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define REP(i,n) for(ll i=0;i<(n);++i)
#define REPR(i,n) for(ll i=n;i>=0;i--)
 
#define FOREACH(x,a) for(auto& (x) : (a) )
 
#define WFA(d,v) REP(k,v)REP(i,v)REP(j,v)d[i][j]=min(d[i][j],d[i][k]+d[k][j])
 
#define SCOUT(x) cout<<(x)<<" "
#define ENDL cout<<endl
 
#define VECCIN(x) for(auto&youso_: (x) )cin>>youso_
#define VECIN2(x,y) REP(i,x.size())cin>>x[i]>>y[i]
#define VECCOUT(x) if(1){for(auto tt=x.begin();tt!=x.end();tt++){if(tt!=x.begin())cout<<" ";cout<<(*tt);}cout<<endl;}
 
#define ALL(obj) (obj).begin(),(obj).end()
 
#define EXIST(n,x) (find(ALL(n),x)!=n.end())
#define UNIQUE(obj) sort(ALL( obj )); obj.erase(unique(ALL(obj)),obj.end())
#define EN(x) if(1){cout<<#x<<endl;return 0;}
#define COUT(x) cout<<(x)<<endl
void CINT(){}
template <class Head,class... Tail>
void CINT(Head&& head,Tail&&... tail){
    cin>>head;
    CINT(move(tail)...);
}
#define CIN(...) int __VA_ARGS__;CINT(__VA_ARGS__)
#define LCIN(...) ll __VA_ARGS__;CINT(__VA_ARGS__)
#define SCIN(...) string __VA_ARGS__;CINT(__VA_ARGS__)
 
template <class T = ll>
T IN(){T x;cin>>x;return (x);}
 
template <class Head>
void VT(Head head){}
template <class Head,class Seco,class... Tail>
void VT(Head&& head,Seco&& seco,Tail&&... tail){
    seco.resize(head);
    VT(head,move(tail)...);
}
void VT2(){}
template <class Head,class... Tail>
void VT2(Head&& head,Tail&&... tail){
  VECCIN(head);
  VT2(move(tail)...);
}
 
template <class Head>
void VT3(Head&& head){}
template <class Head,class Seco,class... Tail>
void VT3(Head&& head,Seco&& seco,Tail&&... tail){
  seco[head]=IN();
  VT3(head,move(tail)...);
}
 
#define VC1(n,...) V __VA_ARGS__;VT(n,__VA_ARGS__);VT2(__VA_ARGS__); //aaabbbccc
#define VC2(n,...) V __VA_ARGS__;VT(n,__VA_ARGS__);REP(i,n)VT3(i,__VA_ARGS__); //abcabcabc
 
// #include <boost/multiprecision/cpp_int.hpp>
// using namespace boost::multiprecision; // cpp_int
 
#define P pair<ll,ll>
#define V vector<ll>
#define M map<ll,ll>
#define S set<ll>
 
#define pb(a) push_back(a)
#define mp make_pair

int main(){
	CIN(n);
	VC1(n,a);
	V rui(n + 1, 0);
	REP(i,n)
		rui[i+1] = rui[i] + a[i];

	// [op,cl)を二等分した場合の差の計算を行う
	
	auto calc = [&](int op, int cl){
		ll sum = rui[cl] - rui[op];
		ll st = op;
		ll en = cl + 1;
		while(en-st>1){
			ll num = (st+en)/2;
			((rui[num] - rui[op] < sum / 2)?st:en) = num;
		}
		return mp(rui[en] - rui[op], rui[cl] - rui[en]);
	};
	auto calc2 = [&](int op, int cl){
		ll sum = rui[cl] - rui[op];
		ll st = op;
		ll en = cl + 1;
		while(en-st>1){
			ll num = (st+en)/2;
			((rui[num] - rui[op] < sum / 2)?st:en) = num;
		}
		return mp(rui[en - 1] - rui[op], rui[cl] - rui[en - 1]);
	};
	ll ans = LINF;
	FOR(i,2,n-1){
		P p1 = calc(0, i);
		P p2 = calc(i, n);
		P p3 = calc2(0, i);
		P p4 = calc2(i, n);
		ans = min(ans, max({p1.second, p2.second, p1.first, p2.first}) - min({p1.first, p2.first, p1.second, p2.second}));
		ans = min(ans, max({p1.second, p4.second, p1.first, p4.first}) - min({p1.first, p4.first, p1.second, p4.second}));
		ans = min(ans, max({p3.second, p4.second, p3.first, p4.first}) - min({p3.first, p4.first, p3.second, p4.second}));
		ans = min(ans, max({p3.second, p2.second, p3.first, p2.first}) - min({p3.first, p2.first, p3.second, p2.second}));
	}
	COUT(ans);
}


Measured memory_bytes: 3328