#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define pb push_back
#define ff first
#define ss second
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n; ll s; cin>>n>>s;
vector<int> g[n + 1], p(n + 1);
vector<ll> a(n + 1);
for (int i = 1; i <= n; i++){
cin>>a[i]>>p[i];
g[p[i]].pb(i);
}
priority_queue<pll> pq[n + 1];
function<void(int, int)> dfs = [&](int v, int pr){
for (int i: g[v]){
if (i == pr) continue;
dfs(i, v);
if (pq[v].size() < pq[i].size()){
swap(pq[v], pq[i]);
}
while (!pq[i].empty()){
auto p = pq[i].top(); pq[i].pop();
pq[v].push(p);
}
}
if (pq[v].empty()){
if (a[v] >= 0){
pq[v].push({a[v], a[v]});
}
return;
}
pll p = {a[v], a[v]};
while (!pq[v].empty() && p.ss < 0){
auto [x, y] = pq[v].top(); pq[v].pop();
p.ff = min(p.ff, p.ss + x);
p.ss += y;
}
if (p.ss > 0) pq[v].push(p);
};
dfs(0, 0);
ll out = 0;
while (!pq[0].empty()){
auto [x, y] = pq[0].top(); pq[0].pop();
if ((s + x) < 0) break;
s += y; out += y;
}
cout<<out<<"\n";
}
