/*
See BOI editorial for Idea.
We just use a multiset to store instead of a set, since there may be duplicates.
Note: Usually, you should try to avoid multisets, however, insertion is only O(log m). Only .count() is running in O(log m + k), so we are safe here.
Removal via keys is O(log m + k) too, however, only amortized only O(log m).
*/
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define tiii tuple<int,int,int>
int mod = 1e9+7;
int INF = numeric_limits<int>::max()/32;
vector<vector<int>> adj;
vector<int>val;
vector<multiset<pii>> order;
void DFS(int v){
for(auto u : adj[v]){
DFS(u);
}
for(auto u : adj[v]){
if(order[u].size() > order[v].size()) swap(order[u],order[v]);
for(auto b : order[u]){
order[v].insert(b);
}
}
pii b = {max(0LL,-val[v]), val[v]};
while(order[v].size() && ( (b.first >= (*(order[v].begin())).first) || b.second <= 0)){
int m,s;
tie(m,s) = *order[v].begin();
order[v].erase(order[v].begin());
b = {max(b.first,m-b.second), b.second+s};
}
if(b.second >= 0) order[v].insert(b);
}
int32_t main(){
int n, s;
cin >> n >> s;
int os = s;
val.resize(n+1);
adj.resize(n+1);
order.resize(n+1);
vector<tiii> nodes;
priority_queue<tiii, vector<tiii>,greater<tiii>> pq;
int c = 0;
int mi = 0;
int req = -1;
vector<int> tba;
for(int i = 1; i <= n; i++){
cin >> val[i];
int p;
cin >> p;
adj[p].push_back(i);
}
DFS(0);
int tot = 0;
vector<pii> blocks(order[0].begin(),order[0].end());
for(auto [mini, profit] : blocks){
assert(profit >= 0);
if(s < mini) break;
s += profit;
}
cout << s-os << "\n";
}
