#include<bits/stdc++.h>
using namespace std;
using i64 = long long;
#define debug false
const int maxn = 3e5;
i64 s;
vector<int> g[maxn+2];
int n , x[maxn+2];
struct NODE{
i64 sum;
i64 require;
bool operator > (const NODE& other) const{
if (require != other.require) return require < other.require;
return sum < other.sum;
}
};
priority_queue<NODE,vector<NODE>,greater<NODE>> bag[maxn+2];
void dfs(int u , int p){
for (auto& v : g[u]){
if (v==p) continue;
dfs(v,u);
if (bag[v].size() > bag[u].size()) swap(bag[u] , bag[v]);
while (bag[v].size()){
bag[u].push(bag[v].top());
bag[v].pop();
}
if (debug){
cout << u << " " << v << '\n';
}
}
i64 sum = x[u] , require = min(0 , x[u]);
while (bag[u].size()){
i64 x = bag[u].top().sum , y = bag[u].top().require;
if (sum < 0){
require = min(require , y + sum);
sum += x;
bag[u].pop();
}
else {
if (require <= y){
sum += x;
bag[u].pop();
continue;
}
bag[u].push({sum , require});
break;
}
}
if (bag[u].size()==0) bag[u].push({sum , require});
if (bag[u].size()==1 && bag[u].top().sum < 0) bag[u].pop();
return;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cin >> n >> s;
for (int i = 1; i <= n; ++i) {
int p; cin >> x[i] >> p;
g[p].push_back(i);
}
i64 profit = 0;
dfs(0,-1);
while (bag[0].size()){
i64 x = bag[0].top().sum , y = bag[0].top().require;
if (debug){
cout << x << ' ' << y << '\n';
}
bag[0].pop();
if (s + profit + y >= 0){
profit += x;
}
}
cout << profit;
}
