#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=3e5+5;
int n, m, a[N];
vector<int> adj[N];
struct DP:map<int, int>{
void pop(int x){
int cur=-x, last=x;
for(map<int, int>::iterator it=begin();it!=end()&&cur<0;it=erase(it)){
if(cur<0){
last=max(last, it->first-cur);
}
cur+=it->second;
}
if(cur>0){
(*this)[last]+=cur;
}
}
}dp[N];
void dfs(int u){
for(int v:adj[u]){
dfs(v);
if(dp[v].size()>dp[u].size()) swap(dp[u], dp[v]);
for(pair<int, int> p:dp[v]){
int x=p.first, y=p.second;
dp[u][x]+=y;
}
}
if(a[u]>=0){
dp[u][0]+=a[u];
}
else dp[u].pop(-a[u]);
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n>>m;
for(int i=1; i<=n; i++){
int p;
cin>>a[i]>>p;
adj[p].push_back(i);
}
dfs(0);
int ans=0;
for(pair<int, int> p:dp[0]){
int x=p.first, y=p.second;
if(x<=m){
m+=y;
ans+=y;
}
}
cout<<ans;
}
