#include <bits/stdc++.h>
using namespace std;
#define SINGLE_TEST 1
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
#define FOR(i, n) for (int(i) = 0; (i) < (n); ++(i))
#define REP(i, k, n) for (int(i) = (k); (i) <= (n); ++(i))
#define REPR(i, k, n) for (int(i) = (k); (i) >= (n); --(i))
#define FORR(x, arr) for (auto &x : arr)
#define FORR2(x, y, arr) for (auto &[x, y] : arr)
#define ALL(a) (a.begin()), (a.end())
#define RALL(a) (a.rbegin()), (a.rend())
#define REVERSE(v) reverse(ALL(v))
#define SZ(x) (int)(x).size()
#define fi first
#define se second
#define debug(x) cerr << #x << " = " << (x) << endl
const int MOD = 1e9 + 7;
const int INF = 1e9;
const ll LLINF = 1e18;
void solve() {
ull n, s; cin >> n >> s;
vl p(n), x(n);
vvi adj(n);
FOR(i, n) {
cin >> x[i] >> p[i];
p[i]--;
if (p[i] >= 0) adj[p[i]].push_back(i);
}
vl need(n), rew(n);
vi alive(n, 1), seen(n);
auto dfs = [&](auto dfs, ll c, int u, int p = -1) -> void {
if (!alive[u] || seen[u]) return;
seen[u] = 1;
c += x[u];
rew[u] = c;
need[u] = min(need[u], c);
if (p >= 0) need[u] = min(need[u], need[p]);
FORR(v, adj[u]) dfs(dfs, c, v, u);
};
ll ans = 0;
while (1) {
fill(ALL(seen), 0);
fill(ALL(need), 0);
fill(ALL(rew), 0);
FOR(i, n) if (alive[i]) dfs(dfs, 0, i);
ll prof = 0, u = -1;
FOR(i, n) if (alive[i] && s+need[i] >= 0) {
if (prof < rew[i]) {
prof = rew[i];
u = i;
}
}
if (prof == 0) break;
while (u >= 0) {
alive[u] = 0;
u = p[u];
}
ans += prof;
if (s+(ull)prof >= LLINF) s = LLINF;
else s += prof;
}
cout << ans << endl;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
#if SINGLE_TEST
solve();
#else
int t;
cin >> t;
while (t--) {
solve();
}
#endif
return 0;
}
