#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2")
#include<bits/stdc++.h>
using namespace std;
// #define int long long
using ll=long long;
const int N=3e5+10;
int n, p[N];
ll s, a[N];
ll f[N], pf[N];
vector<int> g[N];
// vector<int> tr;
void dfs(int u, ll sum){
sum+=a[u];
pf[u]=min(pf[p[u]], sum);
for (int v:g[u]) dfs(v, sum);
f[u]=(s+pf[u]<0?0:a[u]);
for (int v:g[u]) f[u]+=f[v];
f[u]=max(0ll, f[u]);
}
void trace(int u){
if (s+pf[u]<0){
// tr.push_back(u);
return;
}
ll sum=a[u];
for (int v:g[u]) sum+=f[v];
if (f[u]==sum){
a[u]=0;
for (int v:g[u]) trace(v);
}// else tr.push_back(u);
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> s;
for (int i=1; i<=n; ++i){
cin >> a[i] >> p[i];
g[p[i]].push_back(i);
}
ll ans=0;
for (int i=1; i<=n; ++i){
dfs(0, 0);
ans+=f[0];
s+=f[0];
trace(0);
if (!f[0]) break;
// g[0].swap(tr);
// tr.clear();
}
cout << ans << '\n';
return 0;
}
