#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <iomanip>
#include <sys/time.h>
#include <random>
using namespace std;

#define endl '\n'
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define UNIQ(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef complex<double> comp;
typedef vector< vector<ld> > matrix;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
	size_t seed = hash<T>()(x.first);
	return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};
const int inf = 1e9 + 9;
const ll mod = 1e9 + 7;
const double eps = 1e-8;
const double pi = acos(-1);

int n, m, k;
int a[1010], b[1010], c[1010];
int d[1010];

typedef struct {
    int to, cost;
} edge;

vector<edge> G[110];

bool cand[110];

void check(int s) {
    vector<int> vec[2];
    int p = 0;
    vec[p].push_back(s);
    for (int i = 0; i < k; i++, p=1-p) {
        if (vec[p].size() == 0) break;
        for (int v : vec[p]) {
            for (int j = 0; j < G[v].size(); j++) {
                edge w = G[v][j];
                if (w.cost == d[i]) {
                    vec[1-p].push_back(w.to);
                }
            }
        }
        sort(ALL(vec[1-p]));
        UNIQ(vec[1-p]);
        vec[p].clear();
    }
    
    for (int v : vec[p]) {
        cand[v] = true;
    }
}

void solve() {
    for (int i = 0; i < m; i++) {
        G[a[i]].push_back(edge{b[i], c[i]});
        G[b[i]].push_back(edge{a[i], c[i]});
    }

    for (int i = 0; i < n; i++) check(i);

    vector<int> res;
    for (int i = 0; i < n; i++)
        if (cand[i])
            res.push_back(i+1);
    int l = res.size();
    cout << l << endl;
    for (int i = 0; i < l; i++) {
        cout << res[i] << (i==l-1?endl:' ');
    }
}

void input() {
    cin >> n >> m >> k;
    for (int i = 0; i < m; i++) {
        cin >> a[i] >> b[i] >> c[i];
        a[i]--; b[i]--;
    }
    for (int i = 0; i < k; i++) cin >> d[i];
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);

    input();
    solve();
}