// includes #include // macros #define ll long long int #define pb emplace_back #define mk make_pair #define pq priority_queue #define FOR(i, a, b) for(int i=(a);i<(b);++i) #define rep(i, n) FOR(i, 0, n) #define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--) #define all(x) (x).begin(),(x).end() #define sz(x) ((int)(x).size()) #define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end()) #define FI first #define SE second using namespace std; // types typedef pair P; typedef pair Pl; typedef pair Pll; typedef pair Pd; // constants const int inf = 1e9; const ll linf = 1LL << 50; const double EPS = 1e-10; const int mod = 1e9 + 7; // solve template bool chmax(T &a, const T &b){if(a < b){a = b; return 1;} return 0;} template bool chmin(T &a, const T &b){if(a > b){a = b; return 1;} return 0;} template istream &operator>>(istream &is, vector &vec){for(auto &v: vec)is >> v; return is;} vector

edge[101]; int d[1001]; int main(int argc, char const* argv[]) { ios_base::sync_with_stdio(false); cin.tie(0); int n, m, k; cin >> n >> m >> k; rep(i, m){ int a, b; ll c; cin >> a >> b >> c, a--, b--; edge[a].pb(mk(b, c)); edge[b].pb(mk(a, c)); } rep(i, k)cin >> d[i]; set st; rep(i, n){ for(auto p: edge[i]){ if(p.second == d[0]){ st.insert(p.first); st.insert(i); } } } FOR(i, 1, k){ set ns; for(auto itr = st.begin(); itr != st.end(); ++itr){ for(auto e: edge[*itr]){ if(e.second == d[i])ns.insert(e.first); } } swap(ns, st); } cout << st.size() << endl; for(auto itr = st.begin(); itr != st.end(); ++itr){ cout << *itr + 1; auto it = itr; it++; if(it == st.end())cout << endl; else cout << " "; } return 0; }