#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define eb emplace_back
#define pu push
#define ins insert
#define fi first
#define se second
#define all(a) a.begin(),a.end()
#define bruh ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fu(x,a,b) for (auto x=a;x<=b;x++)
#define fd(x,a,b) for (auto x=a;x>=b;x--)
#define int ll
using namespace std;
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
/*
Competitive Programming notes that I need to study & fix my dumbass self:
1. Coding:
- Always be sure to check the memory of arrays (maybe use vectors), for loops
- Always try to maximize the memory if possible, even if you are going for subtasks
- Do not exploit #define int long long, it will kill you
2. Stress:
- Always try generating big testcases and try if they run
3. Time management:
- Don't overcommit or undercommit, always spend a certain amount of time to think a problem, don't just look at it and say I'm fucked
- Do not spend too much time coding brute-force solutions, they should be easily-codable solutions that don't take up too much time
Time management schedule:
Offline / LAH days (4 problems - 3h):
15' thinking of solution / idea
1. no idea: skip
2. yes idea: continue thinking for <= 15'
+ implementing: <= 20'
+ brute-force: <= 5'
+ test generator: <= 5'
I hate offline because I am dumb
*/
typedef pair<int, int> ii;
const int N = 2e5+5;
const int B = 750;
const int mod = 1e9+7;
const int inf = 1e18;
using cd = complex<double>;
const long double PI = acos(-1);
int power(int a,int b) {ll x = 1;if (a >= mod) a%=mod; while (b) {if (b & 1) x = x*a % mod;a = a*a % mod;b>>=1;}return x;}
int n,s;
int a[N], c[N], profit[N];
vector<int> adj[N];
priority_queue<ii, vector<ii>, greater<ii>> q[N];
void merge(int i, int j)
{
if (q[i].size() < q[j].size()) swap(q[i], q[j]);
while (!q[j].empty()) q[i].push(q[j].top()), q[j].pop();
}
void dfs(int u)
{
for (auto v : adj[u]) dfs(v);
q[u].push({c[u], u});
int cur = 0;
while (!q[u].empty())
{
int v = q[u].top().se, cost = q[u].top().fi;
q[u].pop();
if (cost == inf) break;
if (cur < cost) c[u] += cost-cur, cur = cost;
if (v == u)
{
cur += a[v];
for (auto i : adj[u]) q[u].push({c[i], i});
} else
{
cur += profit[v];
merge(u, v);
}
if (cur >= c[u])
{
profit[u] = cur-c[u];
return;
}
}
c[u] = inf;
}
void solve()
{
cin>>n>>s;
for (int i = 1; i <= n; i++)
{
int p;
cin>>a[i]>>p;
adj[p].pb(i);
}
dfs(0);
// for (int i = 0; i <= n; i++) cout<<c[i]<<" ";
// cout<<endl;
priority_queue<ii, vector<ii>, greater<ii>> pq;
pq.push({c[0], 0});
int cur = s;
while (!pq.empty())
{
int cost = pq.top().fi, u = pq.top().se;
pq.pop();
if (cur < cost) break;
cur += a[u];
// cout<<cur<<" ";
for (auto v : adj[u]) pq.push({c[v], v});
}
cout<<cur - s;
}
/*
Go through the mistakes you usually make and revise your code, for god's sake...
*/
signed main()
{
bruh
//freopen("input.inp","r",stdin);
//freopen("output.inp","w",stdout);
int t = 1;
// cin>>t;
while (t--)
{
solve();
cout<<"\n";
}
}
