n = int(input())
t = list(map(int,input().split()))
s = list(map(int,input().split()))
count = 0

for i in range(n):
    if i == 0:
        count += 1
        tmp = t[i] + s[i]
    elif tmp <= s[i]:
        count += 1
        tmp = t[i] + s[i]
    elif tmp >= s[i]:
        continue
print(count)