#include <iostream>
#include <fstream>
#include <queue>
#include <vector>
#include <algorithm>
#include <cmath>
#include <math.h>

using namespace std;

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

const int MAXN = 505;
const int MAXP = 55;
const int INF = 2000000005;

int p, n, m;
vector<pair<int, int> > g[MAXN];
priority_queue<pair<int, int> > q;
int dist[MAXN][MAXN], dest[MAXP];
int cost[MAXP][MAXP][MAXP];

void Dijkstra(int src, int dist[]){
	dist[src] = 0;
	q.push(make_pair(src, 0));

	while(!q.empty()){
		pair<int, int> current = q.top();
		q.pop();

		if(current.second > dist[current.first])
			continue;

		for(int i = 0; i < g[current.first].size(); ++i){
			int newnode = g[current.first][i].first;
			int newcost = g[current.first][i].second;
			if(current.second + newcost < dist[newnode]){
				dist[newnode] = current.second + newcost;
				q.push(make_pair(newnode, dist[newnode])); 
			}

		}
	}
} 

int main(){
	in >> p >> n >> m;
	for(int i = 0; i < m; ++i){
		int x, y, c;
		in >> x >> y >> c;
		g[x].push_back(make_pair(y, c));
		g[y].push_back(make_pair(x, c));
	}
	for(int i = 0; i <= n ; ++i)
    for(int j = 0; j <= n ; ++j)
      dist[i][j] = INF;

  for(int i = 1; i <= p ; ++i)
    	in >> dest[i];

  dest[0] = 1;
  g[0].push_back(make_pair(1, 0));

  for(int i = 0; i <= p ; ++i)
    Dijkstra(dest[i], dist[i]);

  for(int st = p; st >= 1 ; --st)
    for(int dr = st; dr <= p ; ++dr)
      for(int k = 0; k <= p ; ++k){
        cost[st][dr][k] = INF;
  			for(int nod = st; nod <= dr ; ++nod)
        	cost[st][dr][k] = min(cost[st][dr][k], cost[st][nod - 1][nod] + cost[nod + 1][dr][nod] + dist[k][dest[nod]]);
  		}
 	out << cost[1][p][0] << '\n';
	

  return 0;

}