Problem: There are N one-off jobs available. If you take the i-th job and complete it, you will earn the reward of B_i after A_i days from the day you do it.

You can take and complete at most one of these jobs in a day.

However, you cannot retake a job that you have already done.

Find the maximum total reward that you can earn no later than M days from today.

You can already start working today.

Constraints

* All values in input are integers.
* 1 \leq N \leq 10^5
* 1 \leq M \leq 10^5
* 1 \leq A_i \leq 10^5
* 1 \leq B_i \leq 10^4

Input

Input is given from Standard Input in the following format:


N M
A_1 B_1
A_2 B_2
\vdots
A_N B_N


Output

Print the maximum total reward that you can earn no later than M days from today.

Examples

Input

3 4
4 3
4 1
2 2


Output

5


Input

5 3
1 2
1 3
1 4
2 1
2 3


Output

10


Input

1 1
2 1


Output

0

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
#define N 100010
using namespace std;
vector<long long> vp[N];
priority_queue<long long> pq;
long long n,m,a,b,ans=0;
int main(){
	long long i,j,cnt;
	cin>>n>>m;
	for(i=0;i<n;i++)
	{
		cin>>a>>b;
		if(a>m)
		{
			continue;
		}
		vp[a-1].push_back(b);
	}
	for(i=0;i<m;i++)
	{
		for(j=0;j<vp[i].size();j++)
		{
			pq.push(vp[i][j]);
		}
		if(pq.size())
		{	
			ans+=pq.top();
			pq.pop();
		}
	}
	cout<<ans<<endl;
	return 0;
}