This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<bits/stdc++.h>
//#include<chrono>
//#include<random>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef double db;
ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a ;} // greatest common divisor (PGCD)
ll lcm(ll a , ll b) {return (a * b) / gcd(a , b);} // least common multiple (PPCM)
int dx[8] = {1, 0, 0, -1, 1, 1, -1, -1};
int dy[8] = {0, 1, -1, 0, 1, -1, -1, 1};
#define endl "\n"
#define ss second
#define ff first
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define vi vector<int>
#define vii vector<pair<int,int>>
#define vl vector<ll>
#define vll vector<pair<ll,ll>>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pdd  pair<double,double>
#define vdd  vector<pdd>
#define speed ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define pbds tree<pii, null_type, less<pii>,rb_tree_tag, tree_order_statistics_node_update>
using namespace __gnu_pbds;
using namespace std;
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
////////////////////Only Clear Code//////////////////////////
 
void usaco_problem(){
    freopen("milkvisits.in", "r", stdin);
    freopen("milkvisits.out", "w", stdout);
}
 
void init(){
    #ifndef ONLINE_JUDGE
 
freopen("input.txt", "r", stdin);
 
freopen("output.txt", "w", stdout);
 
#endif // ONLINE_JUDGE
}
const int mx = 3e5+5;
const int LOG = 22;
const int inf = 1e9;
const ll mod = 1e9+7;
const int sq = 320;
vi graph[mx];
ll p[mx], arr[mx], deg[mx];
priority_queue<vl> pq;
void dfs(int node, ll cost, ll pf){
    if(pf >= 0){
        pq.push({cost, node, pf});
        return;
    }
    for(int adj : graph[node]){
        dfs(adj, min(0LL, min(cost, pf+arr[adj])), pf + arr[adj]);
    }
}
int32_t main(){
    speed;
    int n;
    ll s;cin >> n >> s;
    for(int i = 1; i <= n;i++){
        cin >> arr[i] >> p[i];
        if(p[i] != 0){
            graph[p[i]].pb(i);
            deg[i]++;
        }
    }
    for(int i = 1; i <= n;i++){
        if(deg[i] == 0){
            dfs(i, min(arr[i], 0LL), arr[i]);
        }
    }
    ll k = s;
    while(!pq.empty()){
        int node = pq.top()[1];
        ll cst = -pq.top()[0];
        ll gain = pq.top()[2];
        pq.pop();
        //cout << node << endl;
        if(k >= cst)k += gain;
        assert(k >= 0);
        for(int i : graph[node]){
            dfs(i, min(arr[i], 0LL), arr[i]);
        }
    }
    cout << k-s << endl;
}
/*
    NEVER GIVE UP!
    DOING SMTHNG IS BETTER THAN DOING NTHNG!!!
    Your Guide when stuck:
    - Continue keyword only after reading the whole input
    - Don't use memset with testcases
    - Check for corner cases(n=1, n=0)
    - Check where you declare n(Be careful of declaring it globally and in main)
*/
Compilation message (stderr)
Main.cpp: In function 'void usaco_problem()':
Main.cpp:36:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |     freopen("milkvisits.in", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:37:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |     freopen("milkvisits.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp: In function 'void init()':
Main.cpp:43:8: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 | freopen("input.txt", "r", stdin);
      | ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:45:8: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 | freopen("output.txt", "w", stdout);
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