#include <bits/stdc++.h>
#define ll long long
#define pii pair <int, int>
#define fi first
#define se second
#define pb push_back
#define pil pair <int, ll> 
#define LL __int128

using namespace std;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
const int N = 65, S = 10005; 
const ll mod = 11920928955078125, inf = 0x3f3f3f3f3f3f3f3f; 
int n, m, c, mk[N][N]; 
ll M, w[N], v[N], k, dis[N][N], f[N][N][S], g[S]; 
vector <pil> e[N];

void dfs (int rt, int p, int fa) {
	for (auto i : e[p]) {
		if (i.fi == fa) continue; 
		dis[rt][i.fi] = dis[rt][p]+i.se; dfs(rt, i.fi, p); 
	}
}

vector <int> td; 
void dp (int p, int fa) {
	if (mk[p][fa]) return; 
	mk[p][fa] = 1; 
	if (w[p] <= m) f[p][fa][w[p]] = v[p]; 
	for (auto i : e[p]) {
		dp(i.fi, p); 
		memset(g, -0x3f, sizeof g);
		td.clear(); 
		for (int j = 0;j <= m;j++) if (f[i.fi][p][j] >= 0) td.pb(j); 
		for (int j = 0;j <= m;j++) {
			if (f[p][fa][j] < 0) continue; 
			for (int z : td) if (j+z <= m) g[j+z] = max(g[j+z], f[i.fi][p][z]+f[p][fa][j]); 
		} 
		memcpy(f[p][fa], g, sizeof g); 
	}
	f[p][fa][0] = 0; 
}

void solve () {
	memset(f, -0x3f, sizeof f); 
	cin >> n >> m >> k >> M;
	for (int i = 1;i <= n;i++) cin >> w[i];
	for (int i = 1;i <= n;i++) cin >> v[i]; 
	for (int i = 1;i < n;i++) {
		int x, y; ll c; cin >> x >> y >> c; 
		e[x].pb({y, c}); e[y].pb({x, c});
	}
	for (int i = 1;i <= n;i++) dfs(i, i, 0); 
	for (int i = 1;i <= n;i++) dp(i, 0); 
	ll ans = -inf; 
	for (int i = 1;i <= n;i++) for (int j = 0;j <= m;j++) ans = max(ans, f[i][0][j]); 
	cout << ans; 
}

signed main () {
	ios::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	int T = 1; 
	while (T--) solve();
	return 0;
}