#include<bits/stdc++.h>
#define int long long
#define up(i,l,r) for(int i=l; i<=r; ++i)
#define dn(i,r,l) for(int i=r; i>=l; --i)
#define pb push_back

using namespace std;

const int N=400005, inf=1ll<<60;

int T, n, t, a, b, tmp, val[N], f[N], g[N], Ans; 
vector<int> to[N];

void dp(int x) {
	f[x]=0, g[x]=inf;
	for(int y:to[x]) {
		dp(y);
		if(!f[y]) f[x]=1;
		g[x]=min(g[x],g[y]);
	}
	if(!f[x]) g[x]=min(g[x],val[x]);
}

void dfs(int x,int lnk) {
	int cnt=0;
	for(int y:to[x]) cnt+=!f[y];
	if(cnt>1||!f[x]&&cnt) return;
	if(!f[x]) {
		if(lnk!=inf) Ans=min(Ans,a*val[x]+b*lnk);
		for(int y:to[x]) if(g[y]!=inf) Ans=min(Ans,a*val[x]+b*g[y]);
	}
	int len=to[x].size(), tot=0;
	vector<int> lkx(len+2), lsy(len+2);
	lkx[0]=lkx[len+1]=lsy[0]=lsy[len+1]=inf;
	for(int y:to[x]) ++tot, lkx[tot]=lsy[tot]=g[y];
	up(i,1,tot) lkx[i]=min(lkx[i],lkx[i-1]);
	dn(i,tot,1) lsy[i]=min(lsy[i],lsy[i+1]);
	tot=0;
	for(int y:to[x]) {
		++tot;
		if(f[x]^f[y]) dfs(y,min(lnk,min(lkx[tot-1],lsy[tot+1])));
	}
	lsy.clear(), lkx.clear();
}

void mian() {
	cin >> n >> t >> a >> b;
	up(i,1,n) to[i].clear();
	up(i,2,n) cin >> tmp, to[tmp].pb(i);
	up(i,1,n) cin >> val[i];
	dp(1);
	if(!t&&f[1]||t&&!f[1]) { cout << 0 << '\n'; return; }
	Ans=inf, dfs(1,inf);
	cout << (Ans==inf?-1:Ans) << '\n';
}

signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> T;
	while(T--) mian();
	return 0;
}