#include <cstdio>
#include <cstring>
#include <vector>
#include <queue>
#include <algorithm>

using namespace std;

#define sz(c) int((c).begin())
#define pb push_back

#define INF 0x3f3f3f3f
#define Nmax 512
#define Pmax 64
#define x first
#define y second

int n, p, m;
int dmin[Nmax];
int c[Nmax][Nmax];
int dest[Pmax];

char viz[Pmax][Pmax][Nmax];
int A[Pmax][Pmax][Nmax];

vector< pair<int, int> > graph[Nmax];
int q[Nmax * Nmax], cap, coada;
char inQ[Nmax];

void readdata()
{
	freopen("team.in", "r", stdin);
	freopen("team.out", "w", stdout);

	scanf("%d\n%d\n%d\n", &p, &n, &m);
	for (int i = 1; i <= m; ++i)
	{
		int a = 0, b = 0, c = 0;
		char s[16]; gets(s);
		char *p = s;
		
		while (*p != ' ') {
			a = a * 10 + (*p) - '0';
			++p;
		}
		++p;

		while (*p != ' ') {
			b = b * 10 + (*p) - '0';
			++p;
		}
		++p;

		while (*p != '\0') {
			c = c * 10 + (*p) - '0';
			++p;
		}

		graph[a].push_back(make_pair(b, c));
		graph[b].push_back(make_pair(a, c));
	}
	for (int i = 1; i <= p; ++i)
		scanf("%d", &dest[i]);

}

int sol(int a, int b, int nod)
{
	if (a > b) return 0;
	if (viz[a][b][nod]) return A[a][b][nod];

	viz[a][b][nod] = 1;

	A[a][b][nod] = INF;
	for (int i = a; i <= b; ++i)
		A[a][b][nod] = min(A[a][b][nod], c[nod][dest[i]] + sol(a, i-1, dest[i]) + sol(i+1, b, dest[i]) );
	return A[a][b][nod];
}

void bellmanFord(int start) {
	memset(dmin, INF, sizeof(dmin));
	dmin[start] = 0;

	memset(inQ, 0, sizeof(inQ));
	inQ[start] = 1;

	q[cap = coada = 0] = start;
	while (cap <= coada) {
		int nod = q[cap++];
		inQ[nod] = 0;

		for (vector< pair<int, int> >::iterator it = graph[nod].begin(); it != graph[nod].end(); ++it)
			if (dmin[it->x] > dmin[nod] + it->y) {
				dmin[it->x] = dmin[nod] + it->y;
				if (!inQ[it->x]) {
					q[++coada] = it->x;
					inQ[it->x] = 1;
				}
			}
	}
}

int main()
{
	readdata();
	for (int i = 1; i <= n; ++i) {
		bellmanFord(i);
		memcpy(c[i], dmin, sizeof(dmin));
	}
	printf("%d\n", sol(1, p, 1));
	return 0;
}