#include<bits/stdc++.h>
using namespace std;
const int maxn = 3e5;
const long long inf = 2e18;
int n;
long long base, res;
set<int> chosen[maxn + 1];
pair<long long, int> a[maxn + 1];
vector<int> adj[maxn + 1];
priority_queue<pair<long long, int>> posi, nega;
struct sct{
long long cost, prof;
inline sct(){
cost = prof = 0;
}
} dp[maxn + 1];
inline void DFS(int u){
if (a[u].first >= 0){
dp[u].cost = 0;
dp[u].prof = a[u].first;
for (int v : adj[u])
DFS(v);
return;
}
else{
dp[u].cost = dp[u].prof = a[u].first;
for (int v : adj[u])
DFS(v);
vector<int> vec;
for (int v : adj[u]) if (dp[v].cost != -inf)
vec.push_back(v);
sort(vec.begin(), vec.end(), [](int i, int j){
return dp[i].cost > dp[j].cost;
});
for (int v : vec){
dp[u].cost = min(dp[u].cost, dp[u].prof + dp[v].cost);
dp[u].prof += dp[v].prof;
chosen[u].insert(v);
if (dp[u].prof > 0) break;
}
}
if (dp[u].prof <= 0){
dp[u].cost = dp[u].prof = -inf;
chosen[u].clear();
}
return;
}
inline void update(int u, bool path){
if (!path){
if (a[u].first >= 0)
posi.push({a[u].first, u});
else if (dp[u].cost != -inf){
nega.push({dp[u].cost, u});
}
}
else{
res += a[u].first;
for (int v : adj[u])
update(v, (chosen[u].find(v) != chosen[u].end()));
}
return;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> base;
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);
}
for (int i = 1; i <= n; ++i) if (a[i].second == 0){
DFS(i);
if (a[i].first >= 0)
posi.push({a[i].first, i});
else if (dp[i].cost != -inf)
nega.push({dp[i].cost, i});
}
// for (int i = 1; i <= n; ++i){
// cout << dp[i].cost << ' ' << dp[i].prof << '\n';
// }
while(!posi.empty() || !nega.empty()){
if (!posi.empty()){
auto [cost, u] = posi.top();
posi.pop();
res += cost;
for (int v : adj[u]){
if (a[v].first >= 0)
posi.push({a[v].first, v});
else if (dp[v].cost != -inf){
nega.push({dp[v].cost, v});
}
}
}
else if (!nega.empty()){
auto [cost, u] = nega.top();
nega.pop();
if (base + res + cost < 0)
break;
update(u, true);
}
}
cout << res;
return 0;
}
