#include "closing.h"
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const long long INF = 1'000'000'000'000'000'001;

vector<long long> dist(ll v, vector<vector<pair<ll, ll>>>& arr) {
	vector<long long> ans(arr.size(), INF);
	ans[v] = 0;
	priority_queue<pair<long long, ll>, vector<pair<long long, ll>>, greater<pair<long long, ll>>> pq;
	pq.emplace(0, v);
	while (!pq.empty()) {
		auto[d, nv] = pq.top();
		pq.pop();
		if (ans[nv] != d) {
			continue;
		}
		for (auto[i, c] : arr[nv]) {
			if (ans[i] > d + c) {
				ans[i] = d + c;
				pq.emplace(d + c, i);
			}
		}
	}
	return ans;
}

void dfs(ll v, vector<bool>& can, vector<bool>& used, vector<vector<pair<ll, ll>>>& arr) {
	if (!can[v]) {
		return;
	}
	used[v] = true;
	for (auto[i, _] : arr[v]) {
		if (!used[i]) {
			dfs(i, can, used, arr);
		}
	}
}

int max_score(int n, int x, int y, long long k, vector<int> u, vector<int> v, vector<int> w) {
	vector<vector<pair<ll, ll>>> arr(n);
	for (ll i = 0; i < n - 1; i++) {
		arr[u[i]].emplace_back(v[i], w[i]);
		arr[v[i]].emplace_back(u[i], w[i]);
	}
	vector<long long> d1 = dist(x, arr), d2 = dist(y, arr);
	vector<vector<bool>> cm1, cm2;
	for (ll i = 0; i < (1 << n); i++) {
		vector<bool> can(n, false);
		for (ll j = 0; j < n; j++) {
			if ((i >> j) & 1) {
				can[j] = true;
			}
		}
		vector<bool> used1(n, false), used2(n, false);
		dfs(x, can, used1, arr);
		dfs(y, can, used2, arr);
		if (can == used1) {
			cm1.push_back(can);
		}
		if (can == used2) {
			cm2.push_back(can);
		}
	}
	ll bans = 0;
	for (auto i : cm1) {
		for (auto j : cm2) {
			long long nc = 0;
			ll nans = 0;
			for (ll k = 0; k < n; k++) {
				if (i[k] && j[k]) {
					nc += max(d1[k], d2[k]);
					nans += 2;
				} else {
					if (i[k]) {
						nc += d1[k];
						nans++;
					} else {
						nc += d2[k];
						nans++;
					}
				}
			}
			if (nc <= k) {
				if (bans < nans) {
					bans = nans;
				}
			}
		}
	}
	return bans;
}

#ifdef LOCAL
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;
}
#endif