#include <iostream>

 #include <cstdio>

 #include <cstdlib>

 #include <cstring>

 using namespace std;

 #define INF 0xfffffff

 const int maxn =  + ;

 int dist[maxn], map[maxn][maxn], vis[maxn];

 int n, m, s;

 void Init()

 {

     for (int i = ; i <= n; i++)

     {

         for (int j = ; j <= n; j++)

             map[i][j] = (i == j ?  : INF);

     }

     int p, q, t, w;

     for (int i = ; i < m; i++)

     {

         scanf("%d%d%d", &p, &q, &t);

         if (map[p][q] > t)

             map[p][q] = t;   // 写成map[p][q] = map[q][p] = t 会wa的！！！

     }

     scanf("%d", &w);

     for (int i = ; i < w; i++)

     {

         scanf("%d", &p);

         map[][p] = map[p][] = ;

     }

     for (int i = ; i <= n; i++)

         dist[i] = map[][i];

 }

 void Dijkstra()

 {

     int u, maxx;

     memset(vis, , sizeof(vis));

     for (int i = ; i <= n; i++)

     {

         maxx = INF;

         for (int j = ; j <= n; j++)

         {

             if (!vis[j] && dist[j] < maxx)

                 maxx = dist[u=j];

         }

         vis[u] = ;

         for (int j = ; j <= n; j++)

         {

             if (dist[j] > dist[u] + map[u][j])

                 dist[j] = dist[u] + map[u][j];

         }

     }

 }

 int main()

 {

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

     {

         Init();

         Dijkstra();

         printf("%d\n", dist[s] == INF ? - : dist[s]);

     }

     return ;

 }