#include<cstdio>
#include<algorithm>
#include<vector>
using namespace std;
int sol,n,i,k,s,m,cost[100005],tata,y,x;
vector<int>v[100006];

int df(int x)
{
	int rez=0,dim=-1;
	vector<int>a;
	for (int j=0;j<v[x].size();j++)
	{
		rez+=df(v[x][j]);
		cost[x]+=cost[v[x][j]];
		a.push_back(cost[v[x][j]]);
		dim++;
	}
	if (cost[x]>k) sort(a.begin(),a.end());
	for (i=dim;i>=0;i--)
	{
		if (cost[x]<=k) break;
		cost[x]-=a[i];
		rez++;
	}
	return rez;
}

int main()
{
	freopen("mese.in","r",stdin);
	freopen("mese.out","w",stdout);
	scanf("%d %d",&n,&k);
	for (i=1;i<=n;i++) 
		{
			scanf("%d %d",&x,&cost[i]);
			if (x) v[x].push_back(i);else tata=i;
	}
	printf("%d\n",df(tata)+1);
	return 0;
}