//Author:xht37
#include <bits/stdc++.h>

#define ui unsigned int
#define ll long long
#define ul unsigned ll
#define ld long double

#define pi pair <int, int>
#define fi first
#define se second
#define mp make_pair

#define ls (p << 1)
#define rs (ls | 1)
#define md ((t[p].l + t[p].r) >> 1)

#define vi vector <int>
#define pb push_back
#define pq priority_queue

#define dbg(x) cerr << #x" = " << x << endl
#define debug(...) fprintf(stderr, __VA_ARGS__)

#define fl(x) freopen(x".in", "r", stdin), freopen(x".out", "w", stdout)

using namespace std;

namespace io {
	const int SI = 1 << 21 | 1;
	char IB[SI], *IS, *IT, OB[SI], *OS = OB, *OT = OS + SI - 1, c, ch[100];
	int f, t;
	#define gc() (IS == IT ? (IT = (IS = IB) + fread(IB, 1, SI, stdin), IS == IT ? EOF : *IS++) : *IS++)
	inline void flush() {
		fwrite(OB, 1, OS - OB, stdout), OS = OB;
	}
	inline void pc(char x) {
		*OS++ = x;
		if (OS == OT) flush();
	}

	template <class I>
	inline void rd(I &x) {
		for (f = 1, c = gc(); c < '0' || c > '9'; c = gc()) if (c == '-') f = -1;
		for (x = 0; c >= '0' && c <= '9'; x = (x << 3) + (x << 1) + (c & 15), c = gc());
		x *= f;
	}
	template <class I>
	inline void rd(I &x, I &y) {
		rd(x), rd(y);
	}
	template <class I>
	inline void rd(I &x, I &y, I &z) {
		rd(x), rd(y), rd(z);
	}
	template <class I>
	inline void rda(I *a, int n) {
		for (int i = 1; i <= n; i++) rd(a[i]);
	}
	inline void rdc(char &c) {
		for (c = gc(); c < 33 || c > 126; c = gc());
	}
	inline void rds(char *s, int &n) {
		for (c = gc(); c < 33 || c > 126; c = gc());
		for (n = 0; c >= 33 && c <= 126; s[++n] = c, c = gc());
		s[n+1] = '\0';
	}
	inline void rds(string &s) {
		for (c = gc(); c < 33 || c > 126; c = gc());
		for (s.clear(); c >= 33 && c <= 126; s.pb(c), c = gc());
	}

	template <class I>
	inline void print(I x, char k = '\n') {
		if (!x) pc('0');
		if (x < 0) pc('-'), x = -x;
		while (x) ch[++t] = x % 10 + '0', x /= 10;
		while (t) pc(ch[t--]);
		pc(k);
	}
	template <class I>
	inline void print(I x, I y) {
		print(x, ' '), print(y);
	}
	template <class I>
	inline void print(I x, I y, I z) {
		print(x, ' '), print(y, ' '), print(z);
	}
	template <class I>
	inline void printa(I *a, int n) {
		for (int i = 1; i <= n; i++) print(a[i], " \n"[i==n]);
	}
	inline void printc(char c) {
		pc(c);
	}
	inline void prints(char *s, int n) {
		for (int i = 1; i <= n; i++) pc(s[i]);
		pc('\n');
	}
	inline void prints(string s) {
		int n = s.length();
		while (t < n) pc(s[t++]);
		pc('\n'), t = 0;
	}
	struct Flush {
		~Flush() {
			flush();
		}
	} flusher;
}
using io::rd;
using io::rda;
using io::rdc;
using io::rds;
using io::print;
using io::printa;
using io::printc;
using io::prints;

const int N = 57;
int n, p[N], t;
vi e[N];
ll x, d, w[N], v[N], c[N];

void dfs(int x) {
	v[x] = 1;
	for (int y : e[x])
		dfs(y), v[x] += v[y], w[x] += w[y];
}

const ll inf = 1e18;
ll W[N<<3|1], V[N<<3|1], f[N*N*N], s, ans;

int main() {
//	fl("b05");
	rd(n), rd(x, d, w[1]), p[1] = 1;
	for (int i = 2, f; i <= n; i++)
		rd(w[i]), rd(f), e[f].pb(i), p[i] = i, c[i] = d;
	dfs(1), c[1] = x / w[1] * v[1];
	sort(p + 1, p + n + 1, [&](int i, int j) {
		return w[i] * v[j] < w[j] * v[i];
	});
//	for (int i = 1; i <= n; i++)
//		debug("%d w = %lld v = %lld c = %lld\n", p[i], w[p[i]], v[p[i]], c[p[i]]);
//	debug("------\n");
	for (int i = 1; i <= n; i++) {
		int p = ::p[i];
		ll c = min(::c[p], (ll)n);
		s += c * v[p];
		ll k = 0, x = 0;
		while (x + (1 << k) <= c)
			x += 1 << k, V[++t] = (1 << k) * v[p], W[t] = (1 << k) * w[p], ++k;
		if (c - x) V[++t] = (c - x) * v[p], W[t] = (c - x) * w[p];
	}
//	for (int i = 1; i <= t; i++)
//		debug("%d w = %lld v = %lld\n", i, W[i], V[i]);
	for (int i = 1; i <= s; i++) f[i] = inf;
	for (int i = 1, k = 0; i <= t; k += V[i++])
		for (int j = k; ~j; j--)
			f[j+V[i]] = min(f[j+V[i]], f[j] + W[i]);
	for (int i = 0; i <= s; i++)
		if (f[i] <= x) {
//			dbg(i);
			ll now = i, sum = f[i];
			for (int j = 1; j <= n; j++) {
				int p = ::p[j];
				ll c = min(::c[p] - min(::c[p], (ll)n), (x - sum) / w[p]);
				now += c * v[p], sum += c * w[p];
			}
			ans = max(ans, now);
		}
	print(ans);
	return 0;
}

Measured memory_bytes: 2816