C++ :

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<climits>
#include<vector>
#include<queue>
#define fir first
#define sec second
using namespace std;
const int N=50010;
typedef pair<int,int> pii;
vector<pii>G[N];
typedef vector<pii>::iterator IT;

int n,m,fa[N],anc[N],pos[N],g[N];
bool cover[N];

void build(int u,int color) {
	if(fa[u]==1)color=u;
	anc[u]=color;
	for(IT it=G[u].begin();it!=G[u].end();it++) {
		int v=it->fir,w=it->sec;
		if(v==fa[u])continue;
		fa[v]=u;
		g[v]=w;
		build(v,color);
	}
}

int P[N][20],k;
int L[N][20];
pii city[N],egg[N];

void init_table() {
	while((1<<(k+1))<n)k++;
	memset(P,-1,sizeof(P));
	for(int i=1;i<=n;i++)P[i][0]=fa[i],L[i][0]=g[i];
	for(int j=1;j<=k;j++)
		for(int i=1;i<=n;i++)
			if(P[i][j-1]!=-1&&P[P[i][j-1]][j-1]!=-1) {
				P[i][j]=P[P[i][j-1]][j-1];
				L[i][j]=L[i][j-1]+L[P[i][j-1]][j-1];
			}
}

pii go(int s,int x) {
	for(int j=k;j>=0;j--)
		if(P[s][j]!=-1&&L[s][j]<=x) {
			x-=L[s][j];
			s=P[s][j];
		}
	return make_pair(s,x);
}

void DP(int u) {
	if(cover[u])return;
	bool isleaf=true;
	for(IT it=G[u].begin();it!=G[u].end();it++) {
		int v=it->fir;
		if(v==fa[u])continue;
		isleaf=false;
		DP(v);
		if(!cover[v]&&u!=1)return;
	}
	if(!isleaf)cover[u]=true;
}

bool cmpii(pii a,pii b) {
	return a.sec<b.sec;
}

bool check(int M) {
	memset(cover,0,sizeof(cover));
	memset(city,0,sizeof(city));
	memset(egg,0,sizeof(egg));
	for(int i=1;i<=m;i++) {
		pii u=go(pos[i],M);
		int s=u.fir;
		int x=u.sec;
		if(s==1)egg[++egg[0].fir]=make_pair(pos[i],x);
		else cover[s]=true;
	}
	DP(1);
	for(IT it=G[1].begin();it!=G[1].end();it++) {
		int v=it->fir;
		if(!cover[v])city[++city[0].fir]=*it;
	}
	if(city[0].fir>egg[0].fir)return 0;
	sort(city+1,city+city[0].fir+1,cmpii);
	sort(egg+1,egg+egg[0].fir+1,cmpii);
	int i,j;
	i=j=1;
	while(j<=city[0].fir) {
		int c=city[j].fir;
		int ct=city[j].sec;
		if(cover[c]) {
			j++;
			continue;
		}
		if(i==egg[0].fir+1)break;
		int e=egg[i].fir;
		int et=egg[i].sec;
		if(!cover[anc[e]]) {
			cover[anc[e]]=true;
			i++;
		} else if(ct<=et) {
			cover[c]=true;
			i++;
			j++;
		} else i++;
	}
	return j==city[0].fir+1;
}

void init() {
	scanf("%d",&n);
	int u,v,w;
	for(int i=1;i<n;i++) {
		scanf("%d%d%d",&u,&v,&w);
		G[u].push_back(make_pair(v,w));
		G[v].push_back(make_pair(u,w));
	}
	fa[1]=-1;
	build(1,0);
	scanf("%d",&m);
	for(int i=1;i<=m;i++)
		scanf("%d",&pos[i]);
	init_table();
}

int work() {
	if(G[1].size()>m)return -1;
	int l=0,r=INT_MAX,M;
	while(l<r) {
		M=(l+r)>>1;
		if(check(M))r=M;
		else l=M+1;
	}
	return r;
}

int main() {
	init();
	printf("%d\n",work());
	return 0;
}