#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");

	
int n, m, p, dest[55];
const int INF = 2000000000;
bool f[505];
vector <pair <int, int> > g[505];
priority_queue <pair <int, int> > q;
int dist[505][505];
int cost[55][55][55];

inline void dijkstra(int nod, int d[]){
    memset(f, 0, sizeof(f));
    q.push(make_pair(0, nod));
    d[nod] = 0;
    while(!q.empty()){
        pair <int, int> aux = q.top();
        q.pop();
        if(!f[aux.second])
        for(int i = 0; i < g[aux.second].size() ; ++i){
        	int newnode = g[aux.second][i].first;
        	int newcost = g[aux.second][i].second;
            if(d[newnode] > d[aux.second] + newcost){
                d[newnode] = d[aux.second] + newcost;
                q.push(make_pair(-d[newnode], newnode));
 
            }
            f[aux.second] = 1;
        }
    }
}
int main(){
    in >> p >> n >> m;
    int x, y, c;
    for(int i = 1; i <= m ; ++i){
        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];
    return 0;
}