#include <bits/stdc++.h>
using namespace std;
#define int long long
#ifdef LOCAL
void debug_out() {cerr<<endl;}
template <typename Head, typename... Tail>
void debug_out(Head _H, Tail... _T) {cerr<<" "<<to_string(_H);debug_out(_T...);}
#define debug(...) cerr<<"["<<#__VA_ARGS__<<"]:",debug_out(__VA_ARGS__)
#else
#define debug(...)
#endif
const int MAXN = 300005;
const int inf=1000000500ll;
const long long oo =1000000000000000500ll;
const int MOD = (int)1e9+7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef pair<int,int> pi;
int n,init;
int A[MAXN], P[MAXN];
vector<int>child[MAXN];
priority_queue<pi> * dfs(int x){
priority_queue<pi> * pq = new priority_queue<pi>();
for(auto v:child[x]){
priority_queue<pi> * c = dfs(v);
if(c->size() > pq->size())swap(c,pq);
while(c->size()){
pq->push(c->top());c->pop();
}
}
if(A[x]>=0){
pq->push({0,A[x]});
} else{
int s=A[x];
while(s<0 && pq->size()){
if(pq->top().second + s < 0){
s+=pq->top().second;
pq->pop();
} else{
pi c=pq->top();
int rem=pq->top().second + s;
pq->pop();
pq->push({c.first,rem});
s=0;
}
}
}
return pq;
}
int32_t main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> init;
for(int i=1;i<=n;i++){
cin>>A[i]>>P[i];
child[P[i]].push_back(i);
}
priority_queue<pi> * pq =dfs(0);
int ans=0;
while(pq->size() && pq->top().first<=init){
ans+=pq->top().second;
pq->pop();
}
cout<<ans;
}
