from heapq import heapify, heappop, heappush

N = int(input())
T = [int(s) for s in input().split()]
S = [int(s) for s in input().split()]

pq = [(s, i) for i, s in enumerate(S)]
heapify(pq)

ans = 0
is_proceed = False

while pq:
    time, idx = heappop(pq)

    if idx == -1:
        is_proceed = False
        continue

    if not is_proceed:
        is_proceed = True
        heappush(pq, (time + T[idx], -1))
        ans += 1

print(ans)