#include <bits/stdc++.h>
using namespace std;

#define M_PI                                                                3.14159265358979323846
using ull = unsigned long long;
using ll = long long;
#define endl "\n"

#define REP(i, n) for (ll i = 0; i < n; i++)
#define REPR(i, n) for (ll i = n; i >= 0; i--)
#define FOR(i, m, n) for (ll i = m; i < n; i++)
#define fill(x, y) memset(x, y, sizeof(x))
#define even(x) (x) % 2 == 0
#define odd(x) (x) % 2 != 0
#define all(x) x.begin(), x.end()
#define pcnt __builtin_popcount
#define buli(x) __builtin_popcountll(x)
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());
#define IN1(type, x) type x; cin >> x;
#define inll(x) ll x; cin >> x;
#define INIT() cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(20)

// these functions return the position of result of Binary Search.
#define LB(s, t, x) (int) (lower_bound(s, t, x) - s)
#define UB(s, t, x) (int) (upper_bound(s, t, x) - s)

const ll MOD_CONST = (ll)(1e9 + 7);
const ll CFM = (ll)(998244353);
ll qp(ll a, ll b, int mo) { ll ans = 1; do { if (b & 1) ans = 1ll * ans * a % mo; a = 1ll * a * a % mo; } while (b >>= 1); return ans; }
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { ll temp = gcd(a, b); return temp ? (a / temp * b) : 0; }
int mDays[] = { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
int dx8[] = { 1, -1, 0, 0, 1, 1, -1, -1 }, dy8[] = { 0, 0, -1, 1, -1, 1, -1, 1 };

template<typename F>
class
#if defined(__has_cpp_attribute) && __has_cpp_attribute(nodiscard)
[[nodiscard]]
#elif defined(__GNUC__) && __GNUC_PREREQ(3, 4)
__attribute__((warn_unused_result))
#endif  // defined(__has_cpp_attribute) && __has_cpp_attribute(nodiscard)
FixPoint : F
{
public:
  explicit constexpr FixPoint(F&& f) noexcept
    : F(std::forward<F>(f))
  {}

  template<typename... Args>
  constexpr decltype(auto)
  operator()(Args&&... args) const
  {
    return F::operator()(*this, std::forward<Args>(args)...);
  }
};  // class FixPoint
template<typename F>
static inline constexpr decltype(auto)
makeFixPoint(F&& f) noexcept {
  return FixPoint<F>{std::forward<F>(f)};
}

template <typename T>
vector<T> make_v(size_t a) { return vector<T>(a); }
template <typename T, typename... Ts>
auto make_v(size_t a, size_t b, Ts... ts) { return vector<decltype(make_v<T>(b, ts...))>(a, make_v<T>(b, ts...)); }
template <typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type
fill_v(T &t, const V &v) { t = v; }
template <typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type
fill_v(T &t, const V &v) { for (auto &e : t) fill_v(e, v); }

template <typename T>
vector<T> pows(int b, int n) { // vec{b^0, b^1, b^2, ...}
    vector<T> ret;
    T x = 1;
    while (ret.size() < n) {
        ret.push_back(x);
        x *= b;
    }
    return ret;
}
template <class T>
bool chmax(T &a, const T &b) { if (a < b) { a = b; return 1; } return 0; }
template <class T>
bool chmin(T &a, const T &b) { if (b < a) { a = b; return 1; } return 0; }

inline tuple<ll, ll> rotate45(tuple<ll, ll> point) { ll x = get<0>(point), y = get<1>(point); return tuple<ll, ll>(x + y, x - y); }
inline bool rangeCheck2D(int nx, int ny, int Width, int Height) { return nx >= 0 and nx < Width and ny >= 0 and ny < Height; }

template <typename T>
vector<T> INPA(ll n) {
	vector<T> x;
	REP(i, n) {
		T tmp; cin >> tmp;
		x.push_back(tmp);
	}
	return move(x);
}
// base^x % MOD  - O(x)
ll p_base(ll base, ll x) {
	ll ans = 1;
	REP(i, x) {
		ans *= base;
		ans %= MOD_CONST;
	}
	return ans;
}
template <typename T>
void out(T o) { cout << o << endl; }
template <typename T>
void out(vector<T> &out) { REP(i, (int)out.size()) { cout << out[i]; if (i == (int)out.size() - 1) cout << endl; else cout << " "; } }
template <typename T>
void out(vector<vector<T>> o) { REP(i, o.size()) out(o[i]); }
void YesNo(bool f) { cout << (f?"Yes":"No") << endl; }
void YESNO(bool f) { cout << (f?"YES":"NO") << endl; }
string i_query(ll x, ll y) {
    cout << "? " << x << " " << y << endl;
    fflush(stdout);
    string ret; cin >> ret;
    return ret;
}
void i_answer(ll ans) {
    cout << "! " << ans << endl;
    fflush(stdout);
} 

// use " for (const auto& e : V)

// lambda expression
// auto f = [](int arg1, double arg2) { return ret; };
// lambda recursion
// auto result = makeFixPoint([&](auto rec, int pos, int v) -> int {
//	   rec(pos, v);
// })(0, 1);
// auto func = makeFixPoint([]() -> int {});
// int ret = func();

// tuple binding
// auto t = make_tuple(0, 0);
// int x, y; tie(x, y) = t;
// auto [x, y] = t;

// for pair
// auto [a, b] = pair<int, int>({v1, v2});

// bitset<N> bs(ini_val); // N must be constant
// bs.reset(); // reset all

class ListG {
public:
    // there's directed edge between A and B
    // if to[A] has element B
    vector<vector<int>> to; 

    map<pair<int, int>, ll> cost;
    void setCost(int u, int v, ll c) { 
        cost[{min(u, v), max(u, v)}] = c;
    }
    ll getCost(int u, int v) {
        return cost[{min(u, v), max(u, v)}];
    }

    ListG(int s) : root(-1) {
        size = s;
        to = make_v<vector<int>>(size);
    }

    void setDirectedEdge(int f, int t) {
        to[f].push_back(t);
    }
    void setIndirectedEdge(int v1, int v2) {
        setDirectedEdge(v1, v2);
        setDirectedEdge(v2, v1);
    }

    void dfs(vector<char> &visiting, vector<char> &visited, int current, vector<vector<int>> &cloop) {
        for (auto&& next : to[current]) {
            if (visited[next]) continue;
            if (visiting[next]) {
                cloop[current].push_back(next);
                visited[next] = 1;
                dfs(visiting, visited, next, cloop);
                visited[next] = 0;
            } else {
                visiting[next] = 1;
                dfs(visiting, visited, next, cloop);
                visiting[next] = 0;
            }
        }
    }

    // return max depth
    int makeTree(int r) {
        root = r;
        p = make_v<int>(size);
        p[root] = -1;
        depth = make_v<int>(size);
        int maxDepth = 0;
        makeFixPoint([&](auto rec, int c, int d) -> void {
            depth[c] = d;
            chmax(maxDepth, d);
            REP(i, to[c].size()) {
                int next = to[c][i];
                if (p[c] == next) continue;
                p[next] = c;
                rec(next, d + 1);
            }
        })(root, 0);
        // count leaf node
        auto idxs = make_v<int>(size);
        iota(all(idxs), 0);
        leaf_idx = set<int>(all(idxs));
        REP(i, size) {
            if (i == root) continue;
            leaf_idx.erase(p[i]);
        }
        return maxDepth;
    }

    void makeEulerTour() {
        assert(root >= 0);
        et_begin = make_v<int>(size);
        et_end = make_v<int>(size);
        tmp_k = 0;
        etdfs(root, -1);
    }

    vector<vector<int>> children() {
        assert(root >= 0);
        auto ret = make_v<vector<int>>(size);
        REP(i, size) {
            int prt = p[i];
            if (prt == -1) continue;
            ret[prt].push_back(i);
        }
        return ret;
    }

    int stronglyConnectedConponent() {
        auto rto = make_v<vector<int>>(size);
        REP(from, size) {
            for (auto&& t : to[from])
                rto[t].push_back(from);
        }
        auto cmp = make_v<int>(size);
        fill_v(cmp, 0);
        auto used = make_v<char>(size);
        fill_v(used, 0);
        vector<int> rets; // return index in order
        REP(i, size) {
            makeFixPoint([&](auto dfs, int v) -> void {
                if (used[v]) return;
                used[v] = 1;
                for (auto&& t : to[v])
                    dfs(t);
                rets.push_back(v);
            })(i);
        }
        fill_v(used, 0);
        int ret = 0;
        REPR(i, rets.size()-1) {
            makeFixPoint([&](auto rdfs, int v, int k) -> void {
                if (used[v]) return;
                used[v] = 1;
                cmp[v] = k;
                for (auto&& rt : rto[v])
                        rdfs(rt, k);
                
                rets.push_back(v);
            })(rets[i], ret++);
        }
        return ret;
    }

    vector<int> topologicalSorted() {
        vector<int> ret;
        auto used = make_v<char>(size);
        fill_v(used, 0);
        REP(i, size) {
            makeFixPoint([&](auto dfs, int v) -> void {
                if (used[v]) return;
                used[v] = 1;
                for (auto&& t : to[v]) 
                    dfs(t);
                ret.push_back(v);
            })(i);
        }
        reverse(all(ret));
        return ret;
    }

    void dfsTree(ListG& dfst) {
        auto visited = make_v<char>(size);
        auto prt = make_v<int>(size);
        fill_v(visited, 0);
        fill_v(prt, 0);
        stack<int> st;
        st.push(0);
        while (st.size()) {
            int c = st.top(); st.pop();
            if (visited[c]) continue;
            visited[c] = 1;
            if (c != 0) dfst.setIndirectedEdge(c, prt[c]);
            for (const auto& next : to[c]) {
                prt[next] = c;
                st.push(next);
            }
        }
    }

    int size, root;
    vector<int> p; // parent for each node. parent of root = -1
    vector<int> depth; // for each node. depth of root node = 0
    vector<int> euler_tour;
    vector<int> et_begin, et_end;
    set<int> leaf_idx;

    int tmp_k;
private:
    void etdfs(int vidx, int pidx) {
        et_begin[vidx] = tmp_k;
        euler_tour.push_back(vidx);
        tmp_k++;
        REP(i, to[vidx].size()) {
            if (to[vidx][i] != pidx) {
                etdfs(to[vidx][i], vidx);
                euler_tour.push_back(vidx);
                tmp_k++;
            }
        }
        et_end[vidx] = tmp_k;
    }
};

int main(void)
{
    INIT(); // comment out for Interective Program

    inll(N); inll(M); inll(K);
    auto a = make_v<int>(M);
    auto b = make_v<int>(M);
    auto c = make_v<ll>(M);
    ListG lg(N+1);
    REP(i, M) {
        cin >> a[i] >> b[i] >> c[i];
        lg.setIndirectedEdge(a[i], b[i]);
        lg.setCost(a[i], b[i], c[i]);
    }
    auto d = INPA<ll>(K);

    set<pair<int, int>> cand; // from to
    REP(i, M) {
        if (c[i] == d[0]) {
            cand.insert({a[i], b[i]});
            cand.insert({b[i], a[i]});
        }
    }

    set<pair<int, int>> ncand;
    FOR(i, 1, K) {
        for (const auto& [from, to] : cand) {
            for (const auto& next : lg.to[to]) {
                if (lg.getCost(to, next) != d[i]) continue;
                ncand.insert({to, next});
            }
            int nto = from;
            for (const auto& next : lg.to[nto]) {
                if (lg.getCost(nto, next) != d[i]) continue;
                ncand.insert({to, next});
            }
        }
        cand = ncand;
        ncand = set<pair<int, int>>();
    }
    auto candd = vector<pair<int, int>>(all(cand));
    auto ans = make_v<int>(cand.size());
    REP(i, cand.size()) ans[i] = candd[i].second;
    UNIQUE(ans);
    out(ans.size());
    sort(all(ans));

    out(ans);

	return 0;
}