#include using namespace std; struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star; #define all(c) (c).begin(), (c).end() #define rall(c) (c).rbegin(), (c).rend() #define vv(type, c, m, n, i) vector> c(m, vector(n, i)) #define mat(type, c, m, n) vector> c(m, vector(n));for(auto& r:c)for(auto& i:r)cin>>i; #define rep(i,a,n) for(int i=(a), i##_len=(n); ii##_len; --i) #define each(x,y) for(auto &(x):(y)) #define var(type, ...)type __VA_ARGS__;Scan(__VA_ARGS__); template void Scan(T& t) { cin >> t; } templatevoid Scan(First& first, Rest&...rest) { cin >> first; Scan(rest...); } #define vec(type, c, n) vector c(n);for(auto& i:c) cin>>i; #define len(x) ((int)(x).size()) #define mp make_pair #define eb emplace_back #define em emplace #define pb pop_back #define fi first #define se second #define get(a, i) get(a) #define bit_count __builtin_popcount typedef long long ll; typedef long double ld; typedef vector vi; typedef vector vd; typedef vector vll; typedef vector vs; typedef vector vb; typedef pair pii; #define mini min_element #define maxi max_element #define sum accumulate #define chmax(a,b) if(ab)a=b template inline void print(T t){cout << t << "\n";} template inline void print(H h, T... t){cout << h << " ";print(t...);} set solve() { map> mmi; map> mpi; set v[2]; var(int, n, m, k); int a, b, c; rep(i, 0, m) { cin >> a >> b >> c; mmi[c][a] = b; mmi[c][b] = a; mpi[c].eb(mp(a, b)); } vec(int, d, k); each(a, mpi[d[0]]) { v[0].em(a.fi); v[0].em(a.se); } if (k == 1) { return v[0]; } int a1 = 0, a2 = 1; rep(i, 1, k) { each(a, v[a1]) { if (mmi[d[i]][a] != 0) { v[a2].em(mmi[d[i]][a]); } } v[a1].clear(); swap(a1, a2); } return v[a1]; } int main() { set a = solve(); vi v(all(a)); sort(all(v)); print(len(v)); rep(i, 0, len(v) - 1) { cout << v[i] << " "; } print(v.back()); return 0; }