Deadline Homework

You have $n$ homework assignments to choose from. Each assignment takes exactly one hour to complete.

Assignment $i$ has a deadline $d_i$ and a score $s_i$. If you spend one full hour on it and finish by the end of hour $d_i$, you earn $s_i$ points. Otherwise, you earn nothing for that assignment.

You can work on at most one assignment in each hour, and you do not have to complete every assignment.

What is the maximum total score you can earn?

Input

The first line contains an integer $n$, the number of assignments.

The next $n$ lines each contain two integers $d_i$ and $s_i$, the deadline and score of one assignment.

Output

Print one integer: the maximum total score you can earn.

Constraints

• $1 \le n \le 2 \cdot 10^5$
• $1 \le d_i \le 10^9$
• $1 \le s_i \le 10^9$

Example 1

4
4 70
1 80
1 30
2 100

250

Explanation

One optimal schedule is:

• hour $1$: take the assignment with deadline $1$ and score $80$
• hour $2$: take the assignment with deadline $2$ and score $100$
• hour $3$: take the assignment with deadline $4$ and score $70$

This earns $80 + 100 + 70 = 250$ points.

Example 2

5
1 10
1 20
1 30
1 40
1 50

50

Example 3

6
2 50
2 10
3 20
3 30
3 40
100 60

180