#include "closing.h"
#include <vector>
#include<bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10, M = 3010;
int n, x, y;
long long k;
long long d[N], dx[N], dy[N];
long long f[M][2 * M];
vector<pair<int, int> > adj[N];
void dfs(int u, int p) {
// cerr << u << " " << p << endl;
for(auto &[v, w] : adj[u]) if (v != p) {
d[v] = d[u] + w;
dfs(v, u);
}
}
int max_score(int N, int X, int Y, long long K,
std::vector<int> U, std::vector<int> V, std::vector<int> W)
{
n = N; x = X; y = Y; k = K;
for(int i = 0; i < n; i++) adj[i].clear();
for(int i = 0; i < n - 1; i++) {
adj[U[i]].emplace_back(V[i], W[i]);
adj[V[i]].emplace_back(U[i], W[i]);
}
d[x] = 0;
dfs(x, x);
for(int i = 0; i < n; i++) dx[i] = d[i];
d[y] = 0;
dfs(y, y);
for(int i = 0; i < n; i++) dy[i] = d[i];
vector<long long> arr;
for(int i = 0; i < n; i++) {
arr.push_back(dx[i]);
arr.push_back(dy[i]);
}
sort(arr.begin(), arr.end());
// for(auto &j : arr) cout << j << " "; cout << endl;
long long cur = 0;
int ans = 0;
for(auto &j : arr) {
if (cur + j <= k) {
cur += j;
ans++;
}
else break;
}
if (n > 3000) return ans;
for(int i = 1; i <= n; i++) for(int j = 0; j <= 2 * n; j++) f[i][j] = 1e16;
for(int i = 0; i < n; i++) for(int j = 0; j <= 2 * i; j++) {
if (dx[i] + dy[i] == dx[y]) {
f[i + 1][j + 1] = min(f[i + 1][j + 1], f[i][j] + min(dx[i], dy[i]));
f[i + 1][j + 2] = min(f[i + 1][j + 2], f[i][j] + max(dx[i], dy[i]));
}
else {
f[i + 1][j] = min(f[i + 1][j], f[i][j]);
f[i + 1][j + 1] = min(f[i + 1][j + 1], f[i][j] + min(dx[i], dy[i]));
f[i + 1][j + 2] = min(f[i + 1][j + 2], f[i][j] + max(dx[i], dy[i]));
}
}
for(int j = 1; j <= 2 * n; j++) if (f[n][j] <= k) ans = max(ans, j);
return ans;
}
#ifdef ngu
int main()
{
freopen ("task.inp", "r", stdin);
freopen ("task.out", "w", stdout);
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;
}
#endif // ngu
