#include <bits/stdc++.h>
    
using namespace std;
    
typedef long long ll;
const int  N = 3e5 + 12, MOD = (int)1e9 + 7;

#define int ll
int n, p[N], x[N];
ll s, d[N];
vector<int> g[N], rt, ord[N];

void prec(int v) {
    d[v] = x[v];
    for(int to:g[v]) {
        prec(to);
        if(d[to] < 0) continue;
        d[v] += d[to];
    }
}
void dfs(int v) {
    if(d[v] < 0) return;
    vector<int> f;
    for(int to:g[v]) {
        dfs(to);
        vector<int> nv;
        int l = 0, r = 0;
        while(l < (int)f.size() || r < (int)ord[to].size()) {
            if(l == (int)f.size() || ((int)r != ord[to].size() && x[ord[to][r]] >= 0)) {
                nv.push_back(ord[to][r]);
                r++;
                continue;
            } 
            if(r == (int)ord[to].size() || x[f[l]] >= 0) {
                nv.push_back(f[l]);
                l++;
                continue;
            }
            int l1 = l + 1, r1 = r + 1;
            ll curl = x[f[l]], curr = x[ord[to][r]], mnl = curl, mnr = curr;
            while(curl < 0 && l1 < (int)f.size()) {
                curl += x[f[l1]];
                l1++;
                mnl = min(mnl, curl);
            }
            while(curr < 0 && r1 < (int)ord[to].size()) {
                curr += x[ord[to][r1]];
                r1++;
                mnr = min(mnr, curr);
            }
            if(mnl > mnr) {
                for(int j = l; j < l1; j++) {
                    nv.push_back(f[j]);
                }
                l = l1;
            } else {
                for(int j = r; j < r1; j++) {
                    nv.push_back(ord[to][j]);
                }
                r = r1;
            }
        }
        f = nv;
    }
    ord[v].push_back(v);
    for(auto j:f) {
        ord[v].push_back(j);
    }
}
void test() {
    cin >> n >> s;
    for(int i = 1; i <= n; i++) {
        cin >> x[i] >> p[i];
        g[p[i]].push_back(i);
    }
    prec(0);
    cout << d[0] << '\n';
    return;
    dfs(0);
    ll st = s, en = s, mx = s;
    for(int i:ord[0]) {
        en += x[i];
        if(en < 0) break;
        mx = max(mx, en);
    }
    cout << mx - st << '\n';
}
int32_t main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0); 

    int t = 1; 
    // cin >> t;

    while(t--) 
        test();

    return 0;
}