#include<bits/stdc++.h>
using namespace std;
const int maxn = 3e5;
int n, target[maxn + 1];
long long s, res;
vector<int> adj[maxn + 1];
pair<long long, int> a[maxn + 1];
priority_queue<pair<long long, int>> posi, nega;
inline long long DFS(int u, long long sum){
sum += a[u].first;
if (sum > 0) return sum;
long long opt = -2e18;
for (int v : adj[u]){
long long k = DFS(v, sum);
if (k > opt){
k = opt;
target[u] = v;
}
}
return min(opt, sum);
}
inline void update(int u, bool path){
if (!path){
if (a[u].first > 0){
posi.push({a[u].first, u});
}
else{
long long k = DFS(u, 0);
if (k > -2e18) nega.push({k, u});
}
}
else{
res += a[u].first;
for (int v : adj[u]){
update(v, (v == target[u]));
}
}
return;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> s;
res = s;
for (int i = 1; i <= n; ++i){
cin >> a[i].first >> a[i].second;
if (a[i].second != 0)
adj[a[i].second].push_back(i);
else{
if (a[i].first > 0) posi.push({a[i].first, i});
else nega.push({a[i].first, i});
}
}
while(!posi.empty() && !nega.empty()){
if (!posi.empty()){
auto [earn, u] = posi.top();
posi.pop();
res += earn;
for (int v : adj[u]){
if (a[v].first > 0){
posi.push({a[v].first, v});
}
else{
long long k = DFS(v, 0);
if (k != -2e18) nega.push({k, v});
}
}
}
else{
auto [cost, u] = nega.top();
nega.pop();
if (res + cost < 0) break;
update(u, 1);
}
}
cout << res - s;
return 0;
}
