import heapq


def solve():
    N = int(input())
    A = list(map(int, input().split()))
    B = list(map(int, input().split()))
    z = [0] * 1500

    def sim(p, mi):
        ms = list(zip(A, z))
        heapq.heapify(ms)
        for j in range(p, p + N):
            k = j % N
            nl = ms[0][0] + B[k] // 2
            if ms[0][1] >= mi:
                return float('inf')
            heapq.heapreplace(ms, (nl, ms[0][1] + 1))
        return max(m[1] for m in ms)

    mi = float('inf')
    for i in range(N):
        mi = min(mi, sim(i, mi))

    print(mi)


if __name__ == '__main__':
    solve()