Allowance

As a reward for record milk production, Farmer Melissa has decided to
start paying Bessie a small weekly allowance.

FM has a set of coins in N (1 <= N <= 20) different denominations,
where each denomination of coin evenly divides the next-larger
denomination.

Using the given set of coins, she would like to pay Bessie at least
some given amount of money C (1 <= C <= 100,000,000) every week.
Please help her compute the maximum number of weeks she can pay
Bessie.

POINTS: 250

PROBLEM NAME: allow.X

INPUT FORMAT:

* Line 1: Two space-separated integers: N and C

* Lines 2..N+1: Each line corresponds to a denomination of coin and
        contains two integers: the value V (1 <= V <= 100,000,000) of
        the denomination, and the number of coins B (1 <= B <=
        1,000,000) of this denomation in Farmer Melissa's possession.

SAMPLE INPUT:

3 6
10 1
1 100
5 120

INPUT DETAILS:

FM would like to pay Bessie 6 cents per week.  He has 100 1-cent coins,
120 5-cent coins, and 1 10-cent coin.

OUTPUT FORMAT:

* Line 1: A single integer that is the number of weeks Farmer Melissa can
        pay Bessie at least C allowance

SAMPLE OUTPUT:

111

OUTPUT DETAILS:

FM can overpay Bessie with the one 10-cent coin for 1 week, then pay Bessie
two 5-cent coins for 10 weeks and then pay Bessie one 1-cent coin and one
5-cent coin for 100 weeks.