#include<bits/stdc++.h>
#define L(i, j, k) for(int i = (j); i <= (k); i++)
#define R(i, j, k) for(int i = (j); i >= (k); i--)
#define ll long long
#define ull unsigned long long 
#define sz(a) ((int) a.size())
#define vi vector<int>
#define me(a, x) memset(a, x, sizeof(a))
using namespace std;
const int N = 1 << 21, L = 5e5, mod = 998244353;
const ll inf = 1.5e18;
vector < pair < int, int > > e[N];
int n;
vector < ll > bfs(int x) {
	vector < ll > dis(n);
	L(i, 0, n - 1) {
		dis[i] = 2e18;
	}
	dis[x] = 0;
	queue < int > q;
	q.push(x);
	while(!q.empty()) {
		int u = q.front();
		q.pop();
		for(auto&v : e[u]) {
			if(dis[v.first] > dis[u] + v.second) {
				dis[v.first] = dis[u] + v.second;
				q.push(v.first);
			}
		}
	}
	return dis;
}
int max_score(int N, int X, int Y, ll K, vi U, vi V, vi W) {
	n = N;
	L(i, 0, n - 1) 
		e[i].clear();
	L(i, 0, N - 2) {
		e[U[i]].emplace_back(V[i], W[i]);
		e[V[i]].emplace_back(U[i], W[i]);
	} 
	auto dis1 = bfs(X);
	auto dis2 = bfs(Y);
	vector < ll > jb;
	L(i, 0, N - 1) {
		jb.emplace_back(dis1[i]), jb.emplace_back(dis2[i]);
	}
	
	int ans = 0;
	ll sum = 0;
	sort(jb.begin(), jb.end());
	for(auto&u : jb) 
		if(sum + u <= K) 
			sum += u, ++ans;
	
	ll dxy = dis1[Y];
	L(i, 0, n - 1) 
		if(dis1[i] > dis2[i]) 
			swap(dis1[i], dis2[i]);
	L(i, 0, n - 1) 
		if(dis1[i] + dis2[i] == dxy) 
			K -= dis1[i], dis2[i] -= dis1[i], dis1[i] = 0;
	
	vi cnt(n);
	
	#define type pair < ll, pair < int, int > >
	#define pq priority_queue < type, vector < type >, greater < type > > 
	pq que1, que2;
	
	auto adjust = [&] (pq &que) {
		while(sz(que)) {
			auto tp = que.top();
			if(cnt[tp.second.first] != tp.second.second) que1.pop();
			else break;
		}
		return ;
	};
	
	L(i, 0, n - 1) {
		cnt[i] = 0;
		que1.push(make_pair(dis1[i], make_pair(i, 0)));
		que1.push(make_pair(dis2[i], make_pair(i, 0)));
	}
	
	int pos = 0;
	while(K >= 0) {
		adjust(que1);
		if(!sz(que1)) {
			break;
		}
		
		auto tmp = que1.top();
		ll val1 = que1.top().first;
		que1.pop(), adjust(que1);
		val1 += sz(que1) ? que1.top().first : inf;
		que1.push(tmp); 
		
		adjust(que2);
		ll val2 = sz(que2) ? que2.top().first : inf; 
		
		if(min(val1, val2) <= K) {
			pos += 2, K -= min(val1, val2);
			if(val1 < val2) {
				int p1 = que1.top().second.first; que1.pop();
				int p2 = que1.top().second.first; que1.pop();
				cnt[p1] += 1, cnt[p2] += 1;
				if(cnt[p1] == 1) 
					que1.push(make_pair(dis2[p1] - dis1[p1], make_pair(p1, 1)));
				if(cnt[p2] == 1) 
					que1.push(make_pair(dis2[p2] - dis1[p2], make_pair(p2, 1)));
			} else {
				int p3 = que2.top().second.first; que2.pop();
				cnt[p3] += 2;
			}
		} else {
			pos += tmp.first <= K;
			break;
		}
	}
	
	return max(pos, ans);
}

//int main() {
//	cout << max_score(7, 0, 2, 10,
// vi{0, 0, 1, 2, 2, 5}, vi{1, 3, 2, 4, 5, 6}, vi{2, 3, 4, 2, 5, 3}) << '\n';
//	cout << max_score(4, 0, 3, 20, vi{0, 1, 2}, vi{1, 2, 3}, vi{18, 1, 19}) << '\n';
//}