#include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
#include<cstring>
#include<cmath>
using namespace std;
int n,m;
int f[305][305],lson[605],rson[605],w[605];
void addedge(int fa,int s)
{
	rson[s]=lson[fa];
	lson[fa]=s;
}
int dfs(int i,int j)
{
	if(f[i][j]!=-1) return f[i][j];
	int ans=-99999;
	ans=max(ans,dfs(rson[i],j));
	for(int k=0;k<=j-1;k++)
		ans=max(ans,dfs(rson[i],j-k-1)+dfs(lson[i],k)+w[i]);
	f[i][j]=ans;
}
int main()
{
//	while(cin>>n>>m)
//	{
	cin>>n>>m;
		memset(lson,-1,sizeof(lson));
		memset(rson,-1,sizeof(rson));
		memset(f,-1,sizeof(f));
//		if(n==0&&m==0)
//			break;
		for(int i=1;i<=n;i++)
		{
			int fa,xf;
			scanf("%d%d",&fa,&xf);
			addedge(fa,i);
			w[i]=xf;
		}
		cout<<dfs(0,m+1);
//	}
	return 0;
}