⑨ likes dumplings best. One day, he had an idea of starting a business. He wanted to open his own dumpling restaurant.

He made a lot of market analysis in advance and purchased kinds of dumplings according to the user's preference. 

Now, he gives inventory and the total value of each  kind of dumplings, and tell you the total market demand for dumplings, please calculate the maximum income he can get.

输入描述:

The first line contains two integers,  and , indicating the number of dumplings and the maximum market demand.
Next  lines, each line contains two integers  and , which respectively represent the quantity and total price of the i-th kind of dumplings.

输出描述:

Output a number to represent the maximum income.
Your answer is considered correct if its absolute or relative error does not exceed .

4 40
30 45
10 28
5 11
40 55

76.50000

Our biggest income strategy should be to sell all the second and third types of dumplings and  of the first type of dumplings, and get 

备注:

It is allowed to take out part of the inventory during sales.