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