#!/usr/bin/env python3

import array
import collections
import heapq


INF = 10 ** 9


def compute_min(n, friend_levels, enemy_levels):
    fs = friend_levels
    es = collections.deque(el // 2 for el in enemy_levels)
    answer = INF
    pq_base = [(f, 0) for f in fs]
    heapq.heapify(pq_base)
    for _ in range(n):
        pq = pq_base[:]
        for e in es:
            s = pq[0]
            new_level = s[0] + e
            new_battles = s[1] + 1
            if new_battles > answer:
                break
            _ = heapq.heapreplace(pq, (new_level, new_battles))
        else:
            answer = min(answer, max(s[1] for s in pq))
        es.rotate()
    return answer


def main():
    n = int(input())
    friend_levels = array.array("I", map(int, input().split()))
    enemy_levels = map(int, input().split())
    print(compute_min(n, friend_levels, enemy_levels))


if __name__ == '__main__':
    main()