#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <fstream>
#include <queue>
#include <complex>

#define INF 1145141919
#define INF_INT_MAX 2147483647
#define INF_LL_MAX 9223372036854775807
#define EPS 1e-10
#define Pi acos(-1)
#define LL long long
#define ULL unsigned long long

using namespace std;

#define MAX_N 1501

LL N;
LL A[MAX_N], B[MAX_N];
const LL GETA = 1000000;

int main() {

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

	LL ans = INF;

	for (int s = 0; s < N; s++){

		priority_queue<LL, vector<LL>, greater<LL> > que;

		for (int q = 0; q < N; q++){
			que.push(A[q] * GETA);
		}

		LL e = s - 1;
		if (e < 0)
			e = N - 1;

		for (LL t = s; ; t++){
			if (t == N)
				t = 0;
			LL Mons = que.top();
			que.pop();
			LL Level = Mons / GETA;
			LL Cnt = Mons % GETA;
			Level += B[t] / 2;
			Cnt++;
			que.push(Level*GETA + Cnt);
			if (t == e)
				break;
		}

		LL ret = 0;

		while (que.size()){
			LL c = que.top();
			que.pop();
			c = c % GETA;
			ret = max(ret, c);
		}

		ans = min(ret, ans);

	}

	cout << ans << endl;

	return 0;
}