#include <bits/stdc++.h>
#include "closing.h"
using namespace std;
#define ll long long
#define vb vector<bool>
#define pb push_back
#define ff(aa, bb, cc) for(ll aa = bb; aa < cc; aa++)
#define vl vector<ll>
#define pll pair<ll, ll>
#define fi first
#define se second
#define ed "\n"
#define all(aaa) aaa.begin(), aaa.end()
#define rall(aaa) aaa.rbegin(), aaa.rend()
ll MOD = 1e9+7;
priority_queue<ll, vector<ll>, greater<ll>> pq;
vector<vector<pll>> conexiones;
ll k;
void dfs(ll cur, ll p, ll sum){
if(sum > k){
return;
}
pq.push(sum);
for(auto &x : conexiones[cur]){
if(x.fi != p){
dfs(x.fi, cur, sum+x.se);
}
}
}
int max_score(int n, int X, int Y, long long K,
std::vector<int> U, std::vector<int> V, std::vector<int> W){
conexiones = vector<vector<pll>>(n);
k = K;
ff(i, 0, n-1){
conexiones[U[i]].pb({V[i], W[i]});
conexiones[V[i]].pb({U[i], W[i]});
}
dfs(X, -1, 0);
dfs(Y, -1, 0);
ll tot = 0, ktot = 0;
while(ktot <= K && !pq.empty()){
ll cur = pq.top();
//cout << ktot << " " << cur << " " << K << ed;
if(ktot+cur > K){
break;
}
else{
ktot += cur;
tot++;
pq.pop();
}
}
while(!pq.empty()){
pq.pop();
}
return tot;
}
/*
int main(){
int Q;
assert(1 == scanf("%d", &Q));
std::vector<int> N(Q), X(Q), Y(Q);
std::vector<long long> K(Q);
std::vector<std::vector<int>> U(Q), V(Q), W(Q);
for (int q = 0; q < Q; q++)
{
assert(4 == scanf("%d %d %d %lld", &N[q], &X[q], &Y[q], &K[q]));
U[q].resize(N[q] - 1);
V[q].resize(N[q] - 1);
W[q].resize(N[q] - 1);
for (int i = 0; i < N[q] - 1; ++i)
{
assert(3 == scanf("%d %d %d", &U[q][i], &V[q][i], &W[q][i]));
}
}
fclose(stdin);
std::vector<int> result(Q);
for (int q = 0; q < Q; q++)
{
result[q] = max_score(N[q], X[q], Y[q], K[q], U[q], V[q], W[q]);
}
for (int q = 0; q < Q; q++)
{
printf("%d\n", result[q]);
}
fclose(stdout);
return 0;
}
*/
