#include<bits/stdc++.h>

 using namespace std;

 typedef unsigned int ui;

 typedef long long ll;

 typedef unsigned long long ull;

 #define pf printf

 #define mem(a,b) memset(a,b,sizeof(a))

 #define prime1 1e9+7

 #define prime2 1e9+9

 #define pi 3.14159265

 #define lson l,mid,rt<<1

 #define rson mid+1,r,rt<<1|1

 #define scand(x) scanf("%llf",&x)

 #define f(i,a,b) for(int i=a;i<=b;i++)

 #define scan(a) scanf("%d",&a)

 #define mp(a,b) make_pair((a),(b))

 #define P pair<int,int>

 #define dbg(args) cout<<#args<<":"<<args<<endl;

 #define inf 0x3f3f3f3f

 const int maxn=1e4;

 int n,m,t,e;

 int head[maxn],in[maxn],nxt[maxn],d[maxn],a[maxn],ans,b;

 bool vis[maxn];

 struct edge{

     int v,w;

 }p[maxn];

 void init()

 {

     e=;

     mem(head,-);

     mem(nxt,-);

     mem(vis,);

 }

 void addedge(int u,int v,int w)

 {

     p[e].v=v;

     p[e].w=w;

     nxt[e]=head[u];

     head[u]=e++;

 }

 void SPFA(int src)

 {

         mem(in,);

         d[src]=;

         queue<int>q;

         q.push(src);

         in[src]=;

         while(!q.empty())

         {

             int now=q.front();

             q.pop();

             in[now]=;

             for(int i=head[now];~i;i=nxt[i])

             {

                 if(d[p[i].v]>d[now]+p[i].w)

                 {

                     d[p[i].v]=d[now]+p[i].w;

                     if(vis[p[i].v])ans=min(ans,d[p[i].v]);

                     if(!in[p[i].v])

                     {

                         in[p[i].v]=;

                         q.push(p[i].v);

                     }

                 }

             }

         }

 }

 int main()

 {

     //freopen("input.txt","r",stdin);

     //freopen("output.txt","w",stdout);

     std::ios::sync_with_stdio(false);

     while(scanf("%d%d%d",&n,&m,&t)!=EOF)

     {

         init();

          ans=inf;

         int u,v,w;

         f(i,,n)

         {

             scanf("%d%d%d",&u,&v,&w);

             addedge(u,v,w);

             addedge(v,u,w);

         }

         f(i,,m)scan(a[i]);

         f(i,,t)

         {

             scan(b);

             vis[b]=;

         }

         f(i,,m)

         {

             SPFA(a[i]);

         }

         pf("%d\n",ans);

     }

  }