#include <bits/stdc++.h>
using namespace std;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin);i<(end);i++)
#define REP(i, n) FOR(i,0,n)
#define IFOR(i, begin, end) for(int i=(end)-1;i>=(begin);i--)
#define IREP(i, n) IFOR(i,0,n)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define all(v) v.begin(),v.end()
#define SZ(v) ((int)v.size())
#define Lower_bound(v, x) distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) distance(v.begin(), upper_bound(v.begin(), v.end(), x))
#define Max(a, b) a = max(a, b)
#define Min(a, b) a = min(a, b)
#define bit(n) (1LL<<(n))
#define bit_exist(x, n) ((x >> n) & 1)
#define debug(x) cout << #x << "=" << x << endl;
#define vdebug(v) cout << #v << "=" << endl; REP(i_debug, v.size()){ cout << v[i_debug] << ","; } cout << endl;
#define mdebug(m) cout << #m << "=" << endl; REP(i_debug, m.size()){ REP(j_debug, m[i_debug].size()){ cout << m[i_debug][j_debug] << ","; } cout << endl;}
#define pb push_back
#define f first
#define s second
#define int long long
#define INF 1000000000000000000
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for (auto &x : v) is >> x; return is; }
template<typename T> ostream &operator<<(ostream &os, vector<T> &v){ for(int i = 0; i < v.size(); i++) { cout << v[i]; if(i != v.size() - 1) cout << endl; }; return os; }
template<typename T> void Out(T x) { cout << x << endl; }
template<typename T1, typename T2> void Ans(bool f, T1 y, T2 n) { if(f) Out(y); else Out(n); }

using vec = vector<int>;
using mat = vector<vec>;
using Pii = pair<int, int>;
using PiP = pair<int, Pii>;
using PPi = pair<Pii, int>;
using Pdi = pair<double, int>;
using bools = vector<bool>;
using pairs = vector<Pii>;

//int dx[4] = {1,0,-1,0};
//int dy[4] = {0,1,0,-1};
//char d[4] = {'D','R','U','L'};

const int mod = 1000000007;
//const int mod = 998244353;
//#define Add(x, y) x = (x + (y)) % mod
//#define Mult(x, y) x = (x * (y)) % mod

struct edge{int to, cost, id;};

class Graph
{
public:
    int N;
    vector<vector<edge>> G;
    vec m, n;

    Graph(int N): N(N){
        G = vector<vector<edge>>(N, vector<edge>(0));
        n = vec(N, 1);
    }

    void add_Directed_edge(int from, int to, int cost = 1, int id = 0){
        G[from].push_back(edge({to, cost, id}));
    }

    void add_Undirected_edge(int v1, int v2, int cost = 1, int id = 0){
        add_Directed_edge(v1, v2, cost, id);
        add_Directed_edge(v2, v1, cost, id);
    }

    void dfs(int v){
        for(auto e:G[v]){
            dfs(e.to);
            n[v] += n[e.to];
            m[v] += m[e.to];
        }
    }

};

signed main(){

    int N, X, D; cin >> N >> X >> D;
    vec m(N), p(N);
    Graph G(N);
    cin >> m[0];
    FOR(i, 1, N){
        cin >> m[i] >> p[i];
        p[i]--;
        G.add_Directed_edge(p[i], i);
    }

    G.m = m;
    G.dfs(0);
    vec v = G.n, c = G.m;
    //vdebug(v);
    //vdebug(c);
    vec z(N, D), zg(N, 0); z[0] = 1000000000;

    vector<Pdi> greedy;
    REP(i, N){
        if(z[i] > N){
            greedy.pb(Pdi((double)v[i] / c[i], i));
            zg[i] = z[i] - N;
            z[i] = N;
        }
    }
    Sort(greedy); Reverse(greedy);

    pairs T;
    REP(i, N){
        REP(j, 100){
            if(z[i] >= bit(j)){
                T.pb(Pii(c[i] * bit(j), v[i] * bit(j)));
                z[i] -= bit(j);
            }else{
                T.pb(Pii(c[i] * z[i], v[i] * z[i]));
                z[i] = 0;
            }
            if(z[i] == 0) break;
        }
    }

    vec dp(N * N * N + 1, INF);
    dp[0] = 0;
    for(auto t: T){
        int C = t.f, V = t.s;
        int MM = N * N * N - V;
        IREP(i, MM + 1) Min(dp[i + V], dp[i] + C);  
    }
    int ans = 0;
    REP(i, N * N * N) if(dp[i] <= X){
        int rest = X - dp[i], tmp = i;
        REP(j, N){
            int j0 = greedy[j].s;
            if(c[j0] * zg[j0] <= rest){
                rest -= c[j0] * zg[j0];
                tmp += v[j0] * zg[j0];
            }else{
                tmp += v[j0] * (rest / c[j0]);
                break;
            }
        }
        Max(ans, tmp);
    }
    Out(ans);

    return 0;
}


Measured memory_bytes: 1280