#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

class InParser {
private:
	FILE *fin;
	char *buff;
	int sp;

	char read_ch() {
		++sp;
		if (sp == 4096) {
			sp = 0;
			fread(buff, 1, 4096, fin);
		}
		return buff[sp];
	}

public:
	InParser(const char* nume) {
		fin = fopen(nume, "r");
		buff = new char[4096]();
		sp = 4095;
	}

	InParser& operator >> (int &n) {
		char c;
		while (!isdigit(c = read_ch()) && c != '-');
		int sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}

	InParser& operator >> (long long &n) {
		char c;
		n = 0;
		while (!isdigit(c = read_ch()) && c != '-');
		long long sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}
} in ("team.in");
ofstream out ("team.out");

#define ll long long
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#define MAX(a, b) (((a) < (b)) ? (b) : (a))

int const nmax = 500;
int const pmax = 50;
int const inf = 1000000000;

struct Edge{
  int to;
  int cost;
};

vector<Edge> g[5 + nmax];
int dp[5 + pmax][5 + pmax][5 + pmax];

int dist[5 + pmax][5 + nmax];
int spec[5 + pmax];
int seen[5 + nmax];
int n;

void bfs(int node, int p){
  queue<int> q;
  q.push(node);
  dist[p][node] = 0;
  for(int i = 1;i <= n;i++)
    seen[i] = 0;

  while(0 < q.size()){
    int newnode = q.front();
    q.pop();
    seen[newnode] = 0;

    for(int h = 0;h < g[newnode].size(); h++){
      Edge e = g[newnode][h];
      if(dist[p][newnode] + e.cost < dist[p][e.to]){
        dist[p][e.to] = dist[p][newnode] + e.cost;
        if(seen[e.to] == 0){
          q.push(e.to);
          seen[e.to] = 1;
        }
      }
    }
  }
}


int main()
{
  int p;
  in >> p >> n;
  int m;
  in >> m;
  for(int i = 0;i <= p; i++)
    for(int j = 1;j <= n;j++)
      dist[i][j] = inf;

  for(int i = 0;i <= p;i++)
    for(int j = 1;j <= p; j++)
      for(int h = j;h <= p; h++)
        dp[i][j][h] = inf;

  for(int i = 1;i <= m; i++){
    int x, y, cost;
    in >> x >> y >> cost;

    g[x].push_back({y, cost});
    g[y].push_back({x, cost});
  }

  spec[0] = 1;
  bfs(1, 0);

  for(int i = 1;i <= p;i++) {
    in >> spec[i];
    bfs(spec[i], i);
  }
  for(int i = 0;i <= p;i++)
    for(int j = 1;j <= p;j++)
      dp[i][j][j] = dist[j][spec[i]];

  for(int h = 1; h <= p - 1; h++){
    for(int j = 1;j <= p - h; j++){
      for(int start = 0; start <= p; start++){
        dp[start][j][j + h] = inf;
        for(int i = j; i <= j + h; i++){
          dp[start][j][j + h] = MIN(dp[start][j][j + h], dist[start][spec[i]] + dp[i][j][i - 1] + dp[i][i + 1][j + h] );
        }
      }
    }
  }

  out << dp[0][1][p] << '\n';

  return 0;
}