#include <iostream>
#include <algorithm>

using namespace std;

typedef long long ll;

struct Piece{
	int top;
	int end;
	ll size;
};

class Baumkuchen{
private:
	int N;
	const int DevideNum;
	ll* A;
	ll* sum;
	Piece* piece;

	void input();
	void newArrays(int n);
	void setSum();
	bool isContainPiece(int i, const Piece& p);
	ll calcPieceSize(const Piece& p);
	Piece cutDivideBaumkuchen(int _top, int _end, ll min_piece_size);
	bool cutOK(ll min_piece_size);

public:
	Baumkuchen(int _DevideNum);
	~Baumkuchen();
	
	ll solve();
};


Baumkuchen::Baumkuchen(int _DevideNum) : N(0), DevideNum(_DevideNum){
	A = NULL;
	sum = NULL;
	piece = NULL;
}

Baumkuchen::~Baumkuchen(){
	delete[] A;
	delete[] sum;
	delete[] piece;
}

void Baumkuchen::newArrays(int n){
	A = new ll[n];
	sum = new ll[2 * n + 1];
	piece = new Piece[DevideNum];
}

void Baumkuchen::input(){
	cin >> N;
	newArrays(N);

	for (int i = 0; i < N; i++) cin >> A[i];
}

void Baumkuchen::setSum(){
	sum[0] = A[0];
	for (int i = 1; i < N; i++) sum[i] = sum[i - 1] + A[i];

	for (int i = 0; i < N; i++) sum[i + N] = sum[i] + sum[N - 1];
}

bool Baumkuchen::isContainPiece(int i, const Piece& p){
	return (p.top <= i%N && i%N <= p.end) || (p.top <= (i%N) + N && (i%N) + N <= p.end);
}

ll Baumkuchen::calcPieceSize(const Piece& p){
	return (p.top <= p.end) ? (sum[p.end] - sum[p.top] + A[p.top % N]) : -1;
}

Piece Baumkuchen::cutDivideBaumkuchen(int _top, int _end, ll min_piece_size){
	Piece p;
	p.top = _top;
	p.end = _end;
	
	if (calcPieceSize(p) < min_piece_size){
		p.size = -1;
		return p;
	}

	int end_max = _end, end_min = _top;

	while (end_max > end_min + 1){
		p.end = (end_max + end_min) / 2;
		if (calcPieceSize(p) < min_piece_size) end_min = p.end;
		else                                   end_max = p.end;
	}
	p.end = end_min;
	p.end = calcPieceSize(p) < min_piece_size ? end_max : end_min;
	p.size = calcPieceSize(p);
	
	return p;
}

bool Baumkuchen::cutOK(ll min_piece_size){
	piece[0] = cutDivideBaumkuchen(0, N - 1, min_piece_size);
	if (piece[0].size == -1) return false;
	
	int cp = piece[0].end;

	for (; isContainPiece(cp, piece[0]); piece[0].top ++){
		piece[0] = cutDivideBaumkuchen(piece[0].top, N - 1, min_piece_size);
		for (int pieceNum = 1; pieceNum < DevideNum; pieceNum++){
			piece[pieceNum] = cutDivideBaumkuchen(piece[pieceNum - 1].end + 1, (piece[0].top) % N + N - 1, min_piece_size);
			if (piece[pieceNum].size == -1) goto MISS;
		}
//		cout << min_piece_size << " : " << piece[0].top << ", " << piece[0].end << ", " << piece[0].size << " | " << piece[1].top << ", " << piece[1].end << ", " << piece[1].size << " | " << piece[2].top << ", " << piece[2].end << ", " << piece[2].size << endl;
		return true;

	MISS:
//		piece[2].size = calcPieceSize(piece[2]);
//		cout << min_piece_size << " : " << piece[0].top << ", " << piece[0].end << ", " << piece[0].size << " | " << piece[1].top << ", " << piece[1].end << ", " << piece[1].size << " | " << piece[2].top << ", " << piece[2].end << ", " << piece[2].size << endl;
		continue;
	}
	return false;
}

ll Baumkuchen::solve(){
	input();
	setSum();
	
	ll ans;
	ll ans_max = sum[N - 1] / 3;
	ll ans_min = 0;

	while (ans_max > ans_min + 1){
		ans = (ans_max + ans_min) / 2;
		if (cutOK(ans)) ans_min = ans;
		else            ans_max = ans;
	}
	ans = (cutOK(ans_min)) ? ans_min : ans_max;

	return ans;
}


int main(){
	Baumkuchen* baumkuchen = new Baumkuchen(3);
	
	ll ans = baumkuchen->solve();
	cout << ans << endl;

	delete baumkuchen;
	return 0;
}

Measured memory_bytes: 3384