```Description

As a reward for record milk production, Farmer John has decided to start paying Bessie
the cow a small weekly allowance. FJ has a set of coins in N (1 <= N <= 20) different
denominations, where each denomination of coin evenly divides the next-larger denomination
(e.g., 1 cent coins, 5 cent coins, 10 cent coins, and 50 cent coins).Using the given set of
coins, he would like to pay Bessie at least some given amount of money C (1 <= C <= 100,000,000)

Input

* 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 John's possession.

Output

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

Sample Input

3 6
10 1
1 100
5 120

Sample Output

111

Hint

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

FJ 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.

Source

USACO 2005 October Silver
```