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 */
#pragma GCC optimize "-oFast"
#include <iostream>
#include <complex>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <numeric>
#include <cstring>
#include <ctime>
#include <cstdlib>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <cmath>
#include <bitset>
#include <cassert>
#include <queue>
#include <stack>
#include <deque>
    
     
using namespace std;
template<typename T1, typename T2>inline void chkmin(T1 &x, T2 y) { if (x > y) x = y; }
template<typename T1, typename T2>inline void chkmax(T1 &x, T2 y) { if (x < y) x = y; } 
template<typename T, typename U> inline ostream &operator<< (ostream &_out, const pair<T, U> &_p) { _out << _p.first << ' ' << _p.second; return _out; }
template<typename T, typename U> inline istream &operator>> (istream &_in, pair<T, U> &_p) { _in >> _p.first >> _p.second; return _in; }
template<typename T> inline ostream &operator<< (ostream &_out, const vector<T> &_v) { if (_v.empty()) { return _out; } _out << _v.front(); for (auto _it = ++_v.begin(); _it != _v.end(); ++_it) { _out << ' ' << *_it; } return _out; }
template<typename T> inline istream &operator>> (istream &_in, vector<T> &_v) { for (auto &_i : _v) { _in >> _i; } return _in; }
template<typename T> inline ostream &operator<< (ostream &_out, const set<T> &_s) { if (_s.empty()) { return _out; } _out << *_s.begin(); for (auto _it = ++_s.begin(); _it != _s.end(); ++_it) { _out << ' ' << *_it; } return _out; }
template<typename T> inline ostream &operator<< (ostream &_out, const multiset<T> &_s) { if (_s.empty()) { return _out; } _out << *_s.begin(); for (auto _it = ++_s.begin(); _it != _s.end(); ++_it) { _out << ' ' << *_it; } return _out; }
template<typename T> inline ostream &operator<< (ostream &_out, const unordered_set<T> &_s) { if (_s.empty()) { return _out; } _out << *_s.begin(); for (auto _it = ++_s.begin(); _it != _s.end(); ++_it) { _out << ' ' << *_it; } return _out; }
template<typename T> inline ostream &operator<< (ostream &_out, const unordered_multiset<T> &_s) { if (_s.empty()) { return _out; } _out << *_s.begin(); for (auto _it = ++_s.begin(); _it != _s.end(); ++_it) { _out << ' ' << *_it; } return _out; }
template<typename T, typename U> inline ostream &operator<< (ostream &_out, const map<T, U> &_m) { if (_m.empty()) { return _out; } _out << '(' << _m.begin()->first << ": " << _m.begin()->second << ')'; for (auto _it = ++_m.begin(); _it != _m.end(); ++_it) { _out << ", (" << _it->first << ": " << _it->second << ')'; } return _out; }
template<typename T, typename U> inline ostream &operator<< (ostream &_out, const unordered_map<T, U> &_m) { if (_m.empty()) { return _out; } _out << '(' << _m.begin()->first << ": " << _m.begin()->second << ')'; for (auto _it = ++_m.begin(); _it != _m.end(); ++_it) { _out << ", (" << _it->first << ": " << _it->second << ')'; } return _out; }
#define sz(c) (int)(c).size()
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define left left228
#define right right228
#define rank rank228
#define y1 y1228                                                         
#define read(FILENAME) freopen((FILENAME + ".in").c_str(), "r", stdin)
#define write(FILENAME) freopen((FILENAME + ".out").c_str(), "w", stdout)
#define files(FILENAME) read(FILENAME), write(FILENAME)
#define pb push_back
const string FILENAME = "input";

struct elems {
    int w, t;
    long long c;
};


int n, x, d;
elems a[53];
int p[53];
long long f[53][53 * 53 * 53];


inline bool comp(const elems &a, const elems &b){
    return a.w * b.c > a.c * b.w;
}


int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    //read(FILENAME);=
    cin >> n >> x >> d >> a[1].c;
    a[1].w = 1;
    a[1].t = 1e9;
    for (int i = 2; i <= n; i++) {
        cin >> a[i].c >> p[i];
        a[i].w = 1;
        a[i].t = d;
    }
    for (int i = n; i > 1; i--) {
        a[p[i]].w += a[i].w;
        a[p[i]].c += a[i].c;
    }
    sort(a + 1, a + n + 1, comp);
    memset(f, 127, sizeof(f));
    f[0][0] = 0;
    for (int i = 1; i <= n; i++) {
        for (int k = 0; k <= min(n, a[i].t); k++) {
            for (int j = 0; j <= n * n * n - k * a[i].w; j++) {
                chkmin(f[i][j + k * a[i].w], f[i - 1][j] + k * a[i].c);
            }
        }
    } 
    int ans = 0;
    for (int i = 0; i <= n * n * n; i++) {
        if (f[n][i] > x) {
            continue;
        }
        int W = x - f[n][i];
        int V = i;
        for (int j = 1; j <= n; j++) {
            int tmp = min(W / a[j].c, (long long)max(0, a[j].t - n));
            W -= tmp * a[j].c;
            V += tmp * a[j].w;
        }
        chkmax(ans, V);
    }
    cout << ans << endl;
    return 0;
}


Measured memory_bytes: 61952