You are given information about n items that you selected in a store.

For each item, you are given P and T.

P denotes the cost of item and T denotes the time needed to check the item by Security.

While security checks that item, you can remove some items from the given selected items.

You take 1 second to steal any of the selected item.

Note: You can only remove items till security is busy in checking.

You want to know the minimum money you have to give to purchase those 'n' items.

Note: You can optimally determine the order of items which security has to check.

Input format: 

The first input line contains number n. 

In each of the following n lines each item is described by a pair of numbers T, P. 

If T = 0, no item can be stolen.

Output format:

Output required answer.

Constraints:

1 <= n <= 2000

0 <= T <= 2000

1 <= P <= 10^9