#include <functional>
#include <list>
#include <string>
#include <vector>
#include <climits>
#include <cstring>
#include <map>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <iostream>
#include <set>
#include <deque>
#include <stack>
#include <cassert>
using namespace std;
#define FOR(i,c) for(__typeof((c).begin()) i=(c).begin();i!=(c).end();i++)
#define ALL(x) (x).begin(),(x).end()
#define CASET2 int ___T, case_n = 1; scanf("%d ", &___T); while ((___T > 0 ? printf("Case #%d:\n", case_n++) : 0), ___T-- > 0)
#define CASET1 int ___T, case_n = 1; scanf("%d ", &___T); while ((___T > 0 ? printf("Case #%d: ", case_n++) : 0), ___T-- > 0)
#define CASET int ___T; scanf("%d ", &___T); while (___T-- > 0)
#define SZ(X) ((int)(X).size())
#define LEN(X) strlen(X)
#define REP(i,n) for(int i=0;i<int(n);i++)
#define REP1(i,a,b) for(int i=(a);i<=int(b);i++)
#define PER1(i,a,b) for(int i=(a);i>=(b);i--)
#define REPL(i,x) for(int i=0;x[i];i++)
#define PER(i,n) for(int i=(n)-1;i>=0;i--)
#define RI1(x) scanf("%d",&x)
#define RI2(x,y) RI1(x), RI1(y)
#define RI3(x,y...) RI1(x), RI2(y)
#define RI4(x,y...) RI1(x), RI3(y)
#define RI5(x,y...) RI1(x), RI4(y)
#define RI6(x,y...) RI1(x), RI5(y)
#define GET_MACRO(_1, _2, _3, _4, _5, _6, NAME, ...) NAME
#define RI(argv...) GET_MACRO(argv, RI6, RI5, RI4, RI3, RI2, RI1)(argv)
#define DRI(argv...) int argv;RI(argv)
#define WRI(argv...) while (RI(argv) != EOF)
#define DWRI(x...) int x; WRI(x)
#define RS(x) scanf("%s",x)
#define MP make_pair
#define PB push_back
#define MS0(x) memset(x,0,sizeof(x))
#define MS1(x) memset(x,-1,sizeof(x))
#define X first
#define Y second
#define V(x) vector<x >

typedef long double LD;
typedef pair<int,int> PII;
typedef vector<int> VI;
typedef long long LL;
const int INF = 1000000000;

void print(int i) { printf("%d", i); }
void print(LL i);
template<class T> void PI(T i) { print(i); puts(""); }
template<class T> void PIS(T i) { print(i); printf(" "); }

template<class T>
void PV(T const &v, int N) {
    REP(i, N) {
        print(v[i]);
        printf("%c", i == N-1 ? '\n' : ' ');
    }
}

template<class T> void PV(T const &v) { PV(v, SZ(v)); }

template<class T, class S> bool has_bit(T mask, S i) { return (mask >> i) & 1; }
long long shift(int i) { return 1ll << i; }

template<class C> void mini(C&a4, C b4){a4=min(a4, b4); }
template<class C> void maxi(C&a4, C b4){a4=max(a4, b4); }
int popcount(int x) { return __builtin_popcount(x); } 
int popcount(long long x) { return __builtin_popcountll(x); } 

#include <unordered_set>
#include <unordered_map>
#define EB emplace_back
#define RL(x) scanf("%lld", &(x))
#define PL(x) printf("%lld\n", x)
#define DRL(x) LL x; RL(x)

int main() {
    DRI(N);
    V(LL) A(N);
    REP(i, N) {
        RL(A[i]);
        if (i) A[i] += A[i-1];
    }
    LL ans = LLONG_MAX; 
    REP1(i, 1, N-3) {
        int j = upper_bound(A.begin(), A.begin() + i, A[i] / 2) - A.begin();
        LL lb1 = LLONG_MIN, ub1 = LLONG_MAX;
        if (j < i) {
            lb1 = max(lb1, min(A[j], A[i] - A[j]));
            ub1 = min(ub1, max(A[j], A[i] - A[j]));
        }
        if (--j >= 0) {
            lb1 = max(lb1, min(A[j], A[i] - A[j]));
            ub1 = min(ub1, max(A[j], A[i] - A[j]));
        }
        j = upper_bound(A.begin() + i + 1, A.end(), (A[i] + A.back()) / 2) - A.begin();
        LL lb2 = LLONG_MIN, ub2 = LLONG_MAX;
        if (j < N) {
            lb2 = max(lb2, min(A[j] - A[i], A.back() - A[j]));
            ub2 = min(ub2, max(A[j] - A[i], A.back() - A[j]));
        }
        if (--j > i) {
            lb2 = max(lb2, min(A[j] - A[i], A.back() - A[j]));
            ub2 = min(ub2, max(A[j] - A[i], A.back() - A[j]));
        }
        ans = min(ans, max(ub1, ub2) - min(lb1, lb2));
    }
    PL(ans);
    return 0;
}


Measured memory_bytes: 1792