#include <iostream>
#include <cstdio>
#include <memory.h>
using namespace std;

int c,wayto[200010],waycost[200010];
bool used[200010],usedt[200010],usedtt[200010];

long long goin(int pos)
{
	memset(usedtt,0,sizeof(usedtt));
	long long cost=0;
	while (pos)
	{
		if (used[pos]||usedtt[pos])
			break;
		usedt[pos]=true;
		usedtt[pos]=true;
		cost+=waycost[pos];
		pos=wayto[pos];
	}
	return(cost);
}

void use(int pos)
{
	while (pos&&!used[pos])
	{
		c--;
		used[pos]=true;
		pos=wayto[pos];
	}
}

int main(void)
{
	freopen("bombb.in","r",stdin);
	freopen("bombb.out","w",stdout);
	int i,n,k,it;
	long long cost,maxcost,total=0;
	cin>>n>>k;
	c=n;
	for (i=1;i<=n;i++)
		cin>>wayto[i]>>waycost[i];
	while (k>0&&c>0)
	{
		k--;
		maxcost=0;
		memset(usedt,0,sizeof(usedt));
		for (i=1;i<=n;i++)
		{
			if (used[i])
				continue;
			if (usedt[i])
				continue;
			cost=goin(i);
			if (maxcost<cost)
			{
				maxcost=cost;
				it=i;
			}
		}
		total+=maxcost;
		use(it);
	}
	cout<<total<<endl;
	return(0);
}