#include // created [2020/05/23] 19:14:32 #pragma GCC diagnostic ignored "-Wsign-compare" #pragma GCC diagnostic ignored "-Wsign-conversion" using i32 = int32_t; using i64 = int64_t; using u32 = uint32_t; using u64 = uint64_t; using uint = unsigned int; using usize = std::size_t; using ll = long long; using ull = unsigned long long; using ld = long double; template using arr = T (&)[n]; template using c_arr = const T (&)[n]; template using max_heap = std::priority_queue; template using min_heap = std::priority_queue, std::greater>; template constexpr T popcount(const T u) { return u ? static_cast(__builtin_popcountll(static_cast(u))) : static_cast(0); } template constexpr T log2p1(const T u) { return u ? static_cast(64 - __builtin_clzll(static_cast(u))) : static_cast(0); } template constexpr T msbp1(const T u) { return log2p1(u); } template constexpr T lsbp1(const T u) { return __builtin_ffsll(u); } template constexpr T clog(const T u) { return u ? log2p1(u - 1) : static_cast(u); } template constexpr bool ispow2(const T u) { return u and (static_cast(u) & static_cast(u - 1)) == 0; } template constexpr T ceil2(const T u) { return static_cast(1) << clog(u); } template constexpr T floor2(const T u) { return u == 0 ? static_cast(0) : static_cast(1) << (log2p1(u) - 1); } template constexpr bool btest(const T mask, const usize ind) { return static_cast((static_cast(mask) >> ind) & static_cast(1)); } template void bset(T& mask, const usize ind) { mask |= (static_cast(1) << ind); } template void breset(T& mask, const usize ind) { mask &= ~(static_cast(1) << ind); } template void bflip(T& mask, const usize ind) { mask ^= (static_cast(1) << ind); } template void bset(T& mask, const usize ind, const bool b) { (b ? bset(mask, ind) : breset(mask, ind)); } template constexpr T bcut(const T mask, const usize ind) { return ind == 0 ? static_cast(0) : static_cast((static_cast(mask) << (64 - ind)) >> (64 - ind)); } template bool chmin(T& a, const T& b) { return (a > b ? a = b, true : false); } template bool chmax(T& a, const T& b) { return (a < b ? a = b, true : false); } constexpr unsigned int mod = 1000000007; template constexpr T inf_v = std::numeric_limits::max() / 4; template constexpr Real pi_v = Real{3.141592653589793238462643383279502884}; auto mfp = [](auto&& f) { return [=](auto&&... args) { return f(f, std::forward(args)...); }; }; template T in() { T v; return std::cin >> v, v; } template T in(const T offset) { return in() - offset; } template T in_v(typename std::enable_if<(i == n), c_arr>::type) { return in(); } template auto in_v(typename std::enable_if<(i < n), c_arr>::type& szs) { const usize s = (usize)szs[i]; std::vector(szs))> ans(s); for (usize j = 0; j < s; j++) { ans[j] = in_v(szs); } return ans; } template auto in_v(c_arr szs) { return in_v(szs); } template T in_v(typename std::enable_if<(i == n), c_arr>::type, const T offset) { return in(offset); } template auto in_v(typename std::enable_if<(i < n), c_arr>::type& szs, const T offset) { const usize s = (usize)szs[i]; std::vector(szs))> ans(s); for (usize j = 0; j < s; j++) { ans[j] = in_v(szs, offset); } return ans; } template auto in_v(c_arr szs, const T offset) { return in_v(szs, offset); } template auto in_t() { return std::tuple...>{in()...}; } template auto in_t(Types... offsets) { return std::tuple...>{in(offsets)...}; } struct io_init { io_init() { std::cin.tie(nullptr), std::ios::sync_with_stdio(false); std::cout << std::fixed << std::setprecision(20); } void clear() { std::cin.tie(), std::ios::sync_with_stdio(true); } } io_setting; int out() { return 0; } template int out(const T& v) { return std::cout << v, 0; } template int out(const std::vector& v) { for (usize i = 0; i < v.size(); i++) { if (i > 0) { std::cout << ' '; } out(v[i]); } return 0; } template int out(const std::pair& v) { return out(v.first), std::cout << ' ', out(v.second), 0; } template int out(const T& v, const Args... args) { return out(v), std::cout << ' ', out(args...), 0; } template int outln(const Args... args) { return out(args...), std::cout << '\n', 0; } template int outel(const Args... args) { return out(args...), std::cout << std::endl, 0; } # define SHOW(...) static_cast(0) constexpr ull TEN(const usize n) { return n == 0 ? 1ULL : TEN(n - 1) * 10ULL; } template auto make_v(typename std::enable_if<(i == n), c_arr>::type, const T& v = T{}) { return v; } template auto make_v(typename std::enable_if<(i < n), c_arr>::type szs, const T& v = T{}) { const usize s = (usize)szs[i]; return std::vector(szs, v))>(s, make_v(szs, v)); } template auto make_v(c_arr szs, const T& t = T{}) { return make_v(szs, t); } template struct edge { using cost_type = Cost; usize u, v; Cost c; edge(const usize u, const usize v) : u{u}, v{v}, c{1} {} edge(const usize u, const usize v, const Cost& c) : u{u}, v{v}, c{c} {} operator usize() const { return v; } usize from() const { return u; } usize to() const { return v; } Cost cost() const { return c; } friend std::ostream& operator<<(std::ostream& os, const edge& e) { return os << e.u << "->" << e.v << ":" << e.c; } }; template class base_graph { public: base_graph(const usize n) : v{n}, es(n), res(n) {} void add_edge(const usize u, const usize v, const bool bi = false) { es[u].emplace_back(u, v), res[v].emplace_back(v, u); if (bi) { es[v].emplace_back(v, u), res[u].emplace_back(u, v); } } template void add_edge(const usize u, const usize v, const Cost& c, const bool bi = false) { es[u].emplace_back(u, v, c), res[v].emplace_back(v, u, c); if (bi) { es[v].emplace_back(v, u, c), res[u].emplace_back(u, v, c); } } std::vector& operator[](const usize u) { return es[u]; } const std::vector& operator[](const usize u) const { return es[u]; } std::vector& from(const usize u) { return es[u]; } const std::vector& from(const usize u) const { return es[u]; } std::vector& to(const usize v) { return res[v]; } const std::vector& to(const usize v) const { return res[v]; } usize size() const { return v; } friend std::ostream& operator<<(std::ostream& os, const base_graph& g) { for (usize i = 0; i < g.v; i++) { for (const auto& e : g.es[i]) { os << e << '\n'; } } return os; } private: usize v; std::vector> es, res; }; template using base_tree = base_graph; using graph = base_graph>; using tree = base_graph>; template using cost_graph = base_graph>; template using cost_tree = base_graph>; template std::pair> top_sort(const base_graph& g) { const usize v = g.size(); std::vector srt, used(v, 0); auto dfs = [&](auto&& self, const usize s) -> bool { if (used[s] == 1) { return false; } else if (used[s] == 0) { used[s] = 1; for (const auto& e : g[s]) { const usize to = e.to(); if (not self(self, to)) { return false; } } used[s] = 2, srt.push_back(s); } return true; }; for (usize i = 0; i < v; i++) { if (not dfs(dfs, i)) { return {false, srt}; } } std::reverse(srt.begin(), srt.end()); return {true, srt}; } class unionfind { public: unionfind(const usize sz) : sz{sz}, rt(sz), comp_sz(sz, 1) { std::iota(rt.begin(), rt.end(), 0); } usize root_of(const usize a) { return assert(a < sz), rt[a] == a ? a : rt[a] = root_of(rt[a]); } bool unite(usize a, usize b) { assert(a < sz), assert(b < sz), a = root_of(a), b = root_of(b); if (a == b) { return false; } if (comp_sz[a] < comp_sz[b]) { std::swap(a, b); } return comp_sz[a] += comp_sz[b], rt[b] = a, true; } usize size_of(const usize a) { return assert(a < sz), comp_sz[root_of(a)]; } friend std::ostream& operator<<(std::ostream& os, const unionfind& uf) { os << "["; for (usize i = 0; i < uf.sz; i++) { os << uf.rt[i] << (i + 1 == uf.sz ? "" : ","); } return (os << "]\n"); } private: const usize sz; std::vector rt, comp_sz; }; int main() { const auto [N, M] = in_t(); std::vector as(M), bs(M), cs(M); unionfind uf(N); for (int i = 0; i < M; i++) { as[i] = in() - 1, bs[i] = in() - 1, cs[i] = in(); if (cs[i] == 1) { if (not uf.unite(as[i], bs[i])) { return outln("Yes"); } } } graph g(N); for (int i = 0; i < M; i++) { if (cs[i] == 2) { g.add_edge(uf.root_of(as[i]), uf.root_of(bs[i])); } } outln(top_sort(g).first ? "No" : "Yes"); }