#include <iostream>
#include <fstream>
#include <string.h>

using namespace std;
const int INF = 0x3F3F3F3F;

int main()
{

    ifstream be("ubuntzei.in");
    ofstream ki("ubuntzei.out");
    int nodes, edges, friends;

    be >> nodes >> edges >> friends;

    int d[nodes][nodes];

    memset(d,INF,sizeof(d));

    for(int i = 0; i < friends ; i++)
    {
        int a;
        be >> a;
    }

    for(int i = 0; i < edges; i++)
    {
        int u,v,cost;
        be >> u >> v >> cost;
        u--; v--;
        d[u][v]=d[v][u]=cost;
    }

    for(int k = 0; k < nodes; k++)
        for(int i = 0; i < nodes; i++)
            for(int j = 0; j < nodes; j++)
                d[i][j] = min(d[i][j],d[i][k]+d[k][j]);

    ki << d[0][nodes-1];

    return 0;
}