**Time limit:**1.00 s**Memory limit:**512 MB

What is your maximum reward if you act optimally?

**Input**

The first input line has an integer $n$: the number of tasks.

After this, there are $n$ lines that describe the tasks. Each line has two integers $a$ and $d$: the duration and deadline of the task.

**Output**

Print one integer: the maximum reward.

**Constraints**

- $1 \le n \le 2 \cdot 10^5$

- $1 \le a,d \le 10^6$

**Example**

Input:

`3`

6 10

8 15

5 12

Output:

`2`