import sys
 
sys.stdin = open('plants.in', 'r')
rints = lambda: [int(x) for x in sys.stdin.readline().split()]
n, a, b, ans = int(input()), rints(), rints(), 0
 
for i in range(1, n):
    a[i] += ans * b[i]
    if b[i - 1] >= b[i]:
        if a[i - 1] > a[i]:
            ans = -1
            break
    else:
        be, en, cur = 0, 10 ** 9, float('inf')
        while be <= en:
            md = (be + en) >> 1
            if a[i - 1] + md * b[i - 1] <= a[i] + md * b[i]:
                en, cur = md - 1, md
            else:
                be = md + 1
        ans = max(ans, cur)
print(ans)
 

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