#include "closing.h"
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define eb emplace_back
#define ALL(a) a.begin(), a.end()
#define ll long long
#define MP make_pair
#define MT make_tuple
#define pii pair<int, int>
#define Info tuple<ll, int, int>
const ll INF = 1ll << 50;
int none(int N, int X, int Y, long long K, std::vector<int> U, std::vector<int> V, std::vector<int> W) {
vector<vector<pii>> adj(N);
for (int i=0; i < N-1; i++) {
adj[V[i]].eb(U[i], W[i]);
adj[U[i]].eb(V[i], W[i]);
}
vector<array<bool, 2>> done(N);
vector<array<ll, 2>> d(N, {INF, INF});
d[X][0] = 0;
d[Y][1] = 0;
priority_queue<Info, vector<Info>, greater<Info>> pq;
pq.emplace(0, X, 0);
pq.emplace(0, Y, 1);
int ans = 0;
while (!pq.empty()) {
auto [_, v, s] = pq.top();
cerr << "(v, s) = " << v << ' ' << s << endl;
pq.pop();
if (done[v][s]) continue;
done[v][s] = true;
if (d[v][s] <= K) ans++, K -= d[v][s];
else break;
for (auto [u, w] : adj[v]) {
ll new_d = d[v][s]+w;
if (done[u][s^1]) new_d = max(new_d - d[u][s^1], 0ll);
if (new_d < d[u][s]) {
d[u][s] = new_d;
pq.push(MT(d[u][s], u, s));
}
}
// auto [_, v] = pq.top();
// pq.pop();
// if (done[v]) continue;
// done[v] = true;
// if (d[v] <= K) {
// ans++;
// K -= d[v];
// }
// for (auto [u, w] : adj[v]) if (d[v]+w < d[u]) {
// d[u] = d[v]+w;
// pq.push(MP(d[u], u));
// }
}
return ans;
}
int max_score(int N, int X, int Y, long long K, std::vector<int> U, std::vector<int> V, std::vector<int> W) {
return none(N, X, Y, K, U, V, W);
}
