rt，只对了#2#3#4#9

#include<bits/stdc++.h>
using namespace std;
#define ll int
const ll N=2e5+9,inf=0x3f3f3f3f;
ll n,m,L,R,u,v,c,C[N<<1],ans=-inf;
ll root,siz[N],maxx[N],Sum;
ll idx,head[N<<1];
bool vis[N];
struct edge
{
	ll to,next,col;
}e[N<<1];
ll cnt;
struct INFO
{
	ll dis,num,b;
}info[N];
bool cmp(INFO x,INFO y)
{
	if(e[x.b].col!=e[y.b].col)return e[x.b].col<e[y.b].col;
	return x.b<y.b;
}
void addedge(ll u,ll v,ll c)
{
	idx++;
	e[idx].to=v;
	e[idx].next=head[u];
	e[idx].col=c;
	head[u]=idx;
}
struct Seg_Tree
{
	ll val[N<<2];
	bool lazy[N<<2];
	void clear()
	{
		val[0]=val[1]=-inf;
		lazy[1]=1;
	}
	void pushdown(ll x)
	{
		val[x<<1]=-inf,lazy[x<<1]=1;
		val[x<<1|1]=-inf,lazy[x<<1|1]=1;
		lazy[x]=0;
	}
	void update(ll x,ll l,ll r,ll p,ll v)
	{
		if(l==r)
		{
			val[x]=v;
			return;
		}
		ll mid=(l+r)>>1;
		val[x]=max(val[x],v);
		if(lazy[x])pushdown(x);
		if(p<=mid)update(x<<1,l,mid,p,v);
		else update(x<<1|1,mid+1,r,p,v);
	}
	ll query(ll x,ll l,ll r,ll Ql,ll Qr)
	{
		if(Ql<=l&&r<=Qr)return val[x];
		ll mid=(l+r)>>1,res=-inf;
		if(lazy[x])return res;
		if(Ql<=mid)res=max(res,query(x<<1,l,mid,Ql,Qr));
		if(mid<Qr)res=max(res,query(x<<1|1,mid+1,r,Ql,Qr));
		return res;
	}
	void U(ll x,ll v)
	{
		update(1,1,n+1,x+1,v);
	}
	ll Q(ll l,ll r)
	{
		if(r<0||l>r)return -inf;
		return query(1,1,n+1,l+1,r+1);
	}
}Ta,Tb;
void getRoot(ll u,ll fa)
{
	siz[u]=1;
	maxx[u]=0;
	for(int i=head[u];i;i=e[i].next)
	{
		ll v=e[i].to;
		if(v==fa||vis[v])continue;
		getRoot(v,u);
		siz[u]+=siz[v];
		maxx[u]=max(maxx[u],siz[v]);
	}
	maxx[u]=max(maxx[u],Sum-siz[u]);
	if(maxx[u]<maxx[root])root=u;
}
void getDis(ll u,ll fa,ll dis,ll num,ll fa_col,ll b)
{
	info[++cnt]=(INFO){dis,num,b};
	for(int i=head[u];i;i=e[i].next)
	{
		ll v=e[i].to,col=e[i].col;
		if(v==fa||vis[v])continue;
		if(fa_col==col)getDis(v,u,dis,num+1,col,b);
		else getDis(v,u,dis+C[col],num+1,col,b);
	}
}
void cal(ll u)
{
	cnt=1;
	info[cnt]=(INFO){0,0,0};
	for(int i=head[u];i;i=e[i].next)
	{
		ll v=e[i].to,col=e[i].col;
		if(vis[v])continue;
		getDis(v,u,C[col],1,col,i);
	}
	sort(info+1,info+cnt+1,cmp);
	Ta.clear();
	Tb.clear();
	for(int a=1,b;a<=cnt;a=b+1)
	{
		for(b=a;b<cnt&&e[info[a].b].col==e[info[b+1].b].col;b++);
		for(int c=a,d;c<=b;c=d+1)
		{
			for(d=c;d<b&&e[info[c].b].col==e[info[d+1].b].col;d++);
			if(c!=a)
			{
				for(int i=c;i<=d;i++)
				{
					ll tem=Tb.Q(L-info[i].num,R-info[i].num);
					ans=max(ans,info[i].dis+tem-C[e[info[i].b].col]);
				}
			}
			for(int i=c;i<=d;i++)
			Tb.U(info[i].num,info[i].dis);
		}
		Tb.clear();
		if(a!=1)
		{
			for(int i=a;i<=b;i++)
			{
				ll tem=Ta.Q(L-info[i].num,R-info[i].num);
				ans=max(ans,info[i].dis+tem);
			}	
		}
		for(int i=a;i<=b;i++)
		Ta.U(info[i].num,info[i].dis);
	}
}
void dfs(ll u)
{
	vis[u]=1;
	cal(u);
//	cout<<ans<<endl;
	for(int i=head[u];i;i=e[i].next)
	{
		ll v=e[i].to;
		if(vis[v])continue;
		root=0;
		Sum=siz[v];
		getRoot(v,u);
		dfs(root);
	}
}
int main()
{
	scanf("%d%d%d%d",&n,&m,&L,&R);
	for(int i=1;i<=m;i++)
	scanf("%d",&C[i]);
	for(int i=1;i<n;i++)
	{
		scanf("%d%d%d",&u,&v,&c);
		addedge(u,v,c);
		addedge(v,u,c);
	}
	root=0;
	Sum=n;
	maxx[root]=inf;
	getRoot(1,0);
	dfs(root);
	printf("%d",ans);
	return 0;
}