#include<bits/stdc++.h>
#define ll long long
#define pll pair<ll, ll>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define ld long double
#define sz(a) ((ll)(a).size())
using namespace std;
const ll maxn=300005;
ll x[maxn], p[maxn];
vector <ll> A[maxn];
priority_queue <pll, vector <pll>, greater<pll>> S[maxn];
void dfs(ll u)
{
for (ll v:A[u])
{
dfs(v);
if (sz(S[v])>sz(S[u])) swap(S[u], S[v]);
while (sz(S[v])) S[u].push(S[v].top()), S[v].pop();
}
if (x[u]>0) S[u].push({0, x[u]});
else
{
ll sus=-x[u], Max=sus;
while (sus>0 && sz(S[u]))
{
auto [c, v]=S[u].top(); S[u].pop();
ll val=min(sus, v);
Max=max(Max, sus+c), sus-=val, v-=val;
if (v) S[u].push({c, v});
}
ll sum=0;
while (sz(S[u]) && S[u].top().fi<Max)
sum+=S[u].top().se, S[u].pop();
S[u].push({Max, sum});
}
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
ll n, s, ans=0; cin >> n >> s;
for (ll i=1; i<=n; i++)
cin >> x[i] >> p[i], A[p[i]].pb(i);
dfs(0);
while (sz(S[0]))
{
auto [c, v]=S[0].top(); S[0].pop();
if (s>=c) s+=v, ans+=v;
}
cout << ans;
}
