#include<stdio.h>
#include<string.h>
#include<queue>
#define INF 0x3f3f3f3f
#define N 1010
#define M 10010
using namespace std;
int head[N],vis[N],dis[N],b[N],e[N],edgenum,T;
struct node{
	int from ,to,cost,next;
}edge[M];
void init(){
	memset(head,-1,sizeof(head));
	edgenum=0;
}
void add(int u,int v,int w){
	node E={u,v,w,head[u]};
	edge[edgenum]=E;
	head[u]=edgenum++;
}
void spfa(int beg){
	queue<int>q;
	memset(vis,0,sizeof(vis));
	memset(dis,INF,sizeof(dis));
	vis[beg]=1;
	dis[beg]=0;
	q.push(beg);
	while(!q.empty()){
		int u=q.front(),i;
		q.pop();
		vis[u]=0;
		for(i=head[u];i!=-1;i=edge[i].next){
			int v=edge[i].to;
			if(dis[v]>dis[u]+edge[i].cost){
				dis[v]=dis[u]+edge[i].cost;
				if(!vis[v]){
					vis[v]=1;
					q.push(v);
				}
			}
		}
	}
}
int main(){
	int beg,end;
	while(scanf("%d%d%d",&T,&beg,&end)!=EOF){
		init();
		while(T--){
			int a,b,cost;
			scanf("%d%d%d",&a,&b,&cost);
			add(a,b,cost);
			add(b,a,cost);//OH ,what a fuck 竟然是双向图。整个人都不好了。 
		}
		int i,j,min;
		for(i=0;i<beg;i++)
			scanf("%d",&b[i]);
		for(i=0;i<end;i++)
			scanf("%d",&e[i]);
		min=INF;
		for(i=0;i<beg;i++){
				spfa(b[i]);
			for(j=0;j<end;j++)
				if(min>dis[e[j]])
					min=dis[e[j]];
		}
	printf("%d\n",min);
	}
	return 0;
}