#include <map>
#include <set>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>

using namespace std;

const int N = 1010;
const int inf = 0x3f3f3f3f;

int dist[N];
int head[N];
int want[N];
int tot, n, m;
typedef pair<int, int> PLL;

struct node
{
    int weight;
    int next;
    int to;
}edge[N * N];

void addedge(int from, int to, int weight)
{
    edge[tot].weight = weight;
    edge[tot].to = to;
    edge[tot].next = head[from];
    head[from] = tot++;
}

void dijkstra(int v0)
{
    memset (dist, inf, sizeof(dist));
    dist[v0] = 0;
    priority_queue < PLL, vector<PLL>, greater<PLL> > qu;
    while (!qu.empty())
    {
        qu.pop();
    }
    dist[v0] = 0;
    qu.push(make_pair(dist[v0], v0));
    while (!qu.empty())
    {
        PLL tmp = qu.top();
        qu.pop();
        int u = tmp.second;
        int d = tmp.first;
        for (int i = head[u]; ~i; i = edge[i].next)
        {
            int v = edge[i].to;
            if (dist[v] > d + edge[i].weight)
            {
                dist[v] = d + edge[i].weight;
                qu.push(make_pair(dist[v], v));
            }
        }
    }
}

int main()
{
    int t, s, d, u, v, w;
    while (~scanf("%d%d%d", &t, &s, &d))
    {
        memset (head, -1, sizeof(head));
        tot = 0;
        for (int i = 0; i < t; ++i)
        {
            scanf("%d%d%d", &u, &v, &w);
            addedge(u, v, w);
            addedge(v, u, w);
        }
        for (int i = 0; i < s; ++i)
        {
            scanf("%d", &u);
            addedge(0, u, 0);
            addedge(u, 0, 0);
        }
        for (int i = 0; i < d; ++i)
        {
            scanf("%d", &want[i]);
        }
        dijkstra(0);
        int ans = inf;
        for (int i = 0; i < d; ++i)
        {
            ans = min(ans, dist[want[i]]);
        }
        printf("%d\n", ans);
    }
    return 0;
}