#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define endl codeforces #define ALL(v) std::begin(v), std::end(v) #define ALLR(v) std::rbegin(v), std::rend(v) using ll = std::int64_t; using ull = std::uint64_t; using pii = std::pair; using tii = std::tuple; using pll = std::pair; using tll = std::tuple; template using vec = std::vector; template using vvec = vec>; template const T& var_min(const T &t) { return t; } template const T& var_max(const T &t) { return t; } template const T& var_min(const T &t, const Tail&... tail) { return std::min(t, var_min(tail...)); } template const T& var_max(const T &t, const Tail&... tail) { return std::max(t, var_max(tail...)); } template void chmin(T &t, const Tail&... tail) { t = var_min(t, tail...); } template void chmax(T &t, const Tail&... tail) { t = var_max(t, tail...); } template const T& clamp(const T &t, const T &low, const T &high) { return std::max(low, std::min(high, t)); } template void chclamp(T &t, const T &low, const T &high) { return t = clamp(t, low, high); } template T make_v(T init) { return init; } template auto make_v(T init, std::size_t s, Tail... tail) { auto v = std::move(make_v(init, tail...)); return vec(s, v); } template struct multi_dem_array { using type = std::array::type, Head>; }; template struct multi_dem_array { using type = std::array; }; template using mdarray = typename multi_dem_array::type; namespace init__ { struct InitIO { InitIO() { std::cin.tie(nullptr); std::ios_base::sync_with_stdio(false); std::cout << std::fixed << std::setprecision(30); } } init_io; } namespace graph { using Node = ll; using Weight = ll; using Edge = std::pair; template struct Graph : public vvec { using vvec::vvec; void add_edge(Node f, Node t, Weight w = 1) { (*this)[f].emplace_back(t, w); if (!Directed) (*this)[t].emplace_back(f, w); } Graph build_inv() const { Graph ret(this->size()); for (Node i = 0; i < this->size(); i++) { for (const Edge &e : (*this)[i]) { Node j; Weight w; std::tie(j, w) = e; if (!Directed && j < i) continue; ret.add_edge(j, i, w); } } return ret; } }; template class dst_iterator { Iterator ite; public: dst_iterator(Iterator ite) : ite(ite) { } bool operator ==(const dst_iterator &oth) const { return ite == oth.ite; } bool operator !=(const dst_iterator &oth) const { return !(*this == oth); } bool operator <(const dst_iterator &oth) const { return ite < oth.ite; } bool operator >(const dst_iterator &oth) const { return ite > oth.ite; } bool operator <=(const dst_iterator &oth) const { return ite <= oth.ite; } bool operator >=(const dst_iterator &oth) const { return ite >= oth.ite; } const Node& operator *() { return ite->first; } const Node& operator *() const { return ite->first; } dst_iterator operator ++() { ++ite; return ite; } }; class dst_iteration { using ite_type = vec::const_iterator; const vec &edges; public: dst_iteration(const vec &edges) : edges(edges) { } auto begin() const { return dst_iterator(edges.cbegin()); } auto end() const { return dst_iterator(edges.cend()); } }; dst_iteration dst(const vec &edges) { return dst_iteration(edges); } } struct Solver { ll n, m; graph::Graph g; std::map st; vec used, pass; Solver(ll n, ll m) : n(n), m(m), g(n), used(n), pass(n) { while (m--) { ll a, b, c; std::cin >> a >> b >> c; a--; b--; g.add_edge(a, b); if (c == 1) g.add_edge(b, a); if (a > b) std::swap(a, b); st[pll(a, b)]++; } } bool dfs(ll cur, ll pre) { used[cur] = true; pass[cur] = true; for (ll nxt : graph::dst(g[cur])) if (nxt != pre) { if (pass[nxt]) return true; if (used[nxt]) continue; if (dfs(nxt, cur)) return true; } pass[cur] = false; return false; } bool solve() { for (auto &&e : st) if (2 <= e.second) return true; for (ll i = 0; i < n; i++) if (!used[i]) { bool res = dfs(i, -1); if (res) return true; } return false; } }; int main() { ll n, m; std::cin >> n >> m; Solver solver(n, m); std::cout << (solver.solve() ? "Yes" : "No") << '\n'; return 0; }