#!/usr/bin/env python3
import itertools

input(), print(
    max(
        (T + s - 1) // s
        for T, s in itertools.accumulate(
            filter(
                lambda x: x[1] != -1,
                sorted(
                    zip(*[map(int, input().split()) for _ in range(2)]),
                    key=lambda x: x[1],
                ),
            ),
            lambda x, y: (x[0] + y[0], y[1]),
        )
    )
)