#include <algorithm>
#include <fstream>
#include <bitset>
#include <vector>
#include <queue>
using namespace std;

#define pb push_back
#define mp make_pair
#define sc second
#define fs first

#define INF 0x3f3f3f3f
#define DIM 505
#define MAX 55

ifstream fin ("team.in");
ofstream fout ("team.out");

vector <pair <int, int> > g[DIM];
int bst[MAX][MAX][MAX];
int D[MAX],dst[DIM];
int cst[MAX][MAX];
bitset <DIM> viz;
int P,N,M;

struct cmp
{
	bool operator()(const int &a, const int &b)
	{
		return dst[a]>dst[b];
	}
}; priority_queue <int,vector <int>,cmp> q;

void read ()
{
    int i,x,y,z;

	fin>>P>>N>>M;
    for (i=1; i<=M; ++i)
    {
        fin>>x>>y>>z;
        g[x].pb (mp (y,z));
        g[y].pb (mp (x,z));
    }
    D[0]=1;
    for (i=1; i<=P; ++i)
        fin>>D[i];
}

void dijkstra (int start)
{
    vector <pair <int,int> > :: iterator it;
    int nod;

	memset(dst,INF,sizeof (dst));
	dst[start]=0;

	for(q.push (start); !q.empty (); )
	{
		nod=q.top (); q.pop (); viz[nod]=0;

		for (it=g[nod].begin (); it!=g[nod].end (); ++it)
			if(dst[nod]+it->sc<dst[it->fs])
			{
				dst[it->fs]=dst[nod]+it->sc;
				if(!viz[it->fs])
				{
					viz[it->fs]=1;
					q.push (it->fs);
				}
			}
	}
}

int calc (int x,int y,int nod)
{
    int i;

    if (x>y)
        return 0;
    if (bst[x][y][nod]<INF)
        return bst[x][y][nod];

    for (i=x; i<=y; ++i)
        bst[x][y][nod]=min (bst[x][y][nod],calc (x,i-1,i)+calc (i+1,y,i)+cst[nod][i]);

    return bst[x][y][nod];
}

void solve ()
{
    int i,j;

    for (i=0; i<=P; ++i)
    {
        dijkstra (D[i]);
        for (j=0; j<=P; ++j)
            cst[i][j]=dst[D[j]];
    }

	memset (bst,INF,sizeof (bst));
	fout<<calc (1,P,0);
}

int main()
{
	read ();
	solve ();

	return 0;
}