#include<iostream>
#include<queue>
#include<cstring>
#include<cstdio>
#define maxn 1090
using namespace std;

int t,s,dd,ans,x,y,z,sumedge,maxnode;
int head[maxn],dis[maxn],vis[maxn],wango[maxn];
queue<int>q;

struct Edge{
    int x,y,z,nxt;
    Edge(int x=0,int y=0,int z=0,int nxt=0):
        x(x),y(y),z(z),nxt(nxt){}
}edge[maxn<<1];

void add(int x,int y,int z){
    edge[++sumedge]=Edge(x,y,z,head[x]);
    head[x]=sumedge;
}

void spfa(){
    memset(vis,0,sizeof(vis));vis[0]=1;q.push(0);
    memset(dis,0x3f,sizeof(dis));dis[0]=0;
    while(!q.empty()){
        int now=q.front();q.pop();vis[now]=0;
        for(register int i=head[now];i;i=edge[i].nxt){
             register int v=edge[i].y;
            if(dis[v]>dis[now]+edge[i].z){
                dis[v]=dis[now]+edge[i].z;
                if(vis[v]==0)vis[v]=1,q.push(v);
            }
        }
    }
}
int main(){
    
    while(~scanf("%d%d%d",&t,&s,&dd)){
        sumedge=0;
        memset(head,0,sizeof(head));
    for(register int i=1;i<=t;i++){
        scanf("%d%d%d",&x,&y,&z);
         add(x,y,z);add(y,x,z);
    }
    for(register int i=1;i<=s;i++){
        scanf("%d",&x);
        add(0,x,0);add(x,0,0);
    }
    for(register int i=1;i<=dd;i++)scanf("%d",&wango[i]);
    spfa();ans=0x7fffffff;
    for(register int i=1;i<=dd;i++)ans=min(ans,dis[wango[i]]);
    printf("%d\n",ans);
    } return 0;
}