import java.io.BufferedReader import java.io.InputStream import java.io.InputStreamReader import java.util.* import kotlin.math.abs import kotlin.math.max import kotlin.math.min val MOD = 1_000_000_007L class UnionFind(n: Int) { private val par = IntArray(n){it} val rank = IntArray(n){1} // 集合の要素数 private val visits = IntArray(n) // 訪れた場所をfind毎に用意するのがもったいないのでつかいまわす fun find(x: Int): Int { var ptr = 0 var i = x while(par[i] != i) { visits[ptr++] = i i = par[i] } repeat(ptr){ par[visits[it]] = i } return i } private fun merge(node: Int, rt: Int): Int { par[node] = rt rank[rt] += rank[node] return rt } fun unite(x: Int, y: Int): Boolean { val x1 = find(x) val y1 = find(y) return if (x1 == y1) false else { if (rank[x1] < rank[y1]) merge(x1, y1) else merge(y1, x1) true } } /** * xを解決する必要がないときは直にrankをみる */ fun cntNodes(x: Int): Int = rank[find(x)] } data class Edge(val a: Int, val b: Int, val tpe: Int) class Solver(stream: InputStream, private val out: java.io.PrintWriter) { fun solve() { val N = ni() val M = ni() val E = Array(M){Edge(ni() - 1, ni() - 1, ni())} val uf = UnionFind(N) for (e in E) { if (e.tpe == 1) { if (!uf.unite(e.a, e.b)) { out.println("Yes") return } } } val id = IntArray(N){it} for (v in 0 until N) { id[v] = uf.find(v) } val outs = Array(N){ mutableListOf()} val ins = IntArray(N) val que = java.util.ArrayDeque() for (e in E) { if (e.tpe != 2) continue outs[id[e.a]].add(id[e.b]) ins[id[e.b]]++ } for (v in 0 until N) { if (ins[v] == 0) que.add(v) } while(que.isNotEmpty()) { val v = que.poll() for (u in outs[v]) { if (--ins[u] == 0) que.add(u) } } val ok = ins.any { it > 0 } out.println(if (ok) "Yes" else "No") } private val isDebug = try { // なんか本番でエラーでる System.getenv("MY_DEBUG") != null } catch (t: Throwable) { false } private var tokenizer: StringTokenizer? = null private val reader = BufferedReader(InputStreamReader(stream), 32768) private fun next(): String { while (tokenizer == null || !tokenizer!!.hasMoreTokens()) { tokenizer = StringTokenizer(reader.readLine()) } return tokenizer!!.nextToken() } private fun ni() = next().toInt() private fun nl() = next().toLong() private fun ns() = next() private fun na(n: Int, offset: Int = 0): IntArray { return map(n) { ni() + offset } } private fun nal(n: Int, offset: Int = 0): LongArray { val res = LongArray(n) for (i in 0 until n) { res[i] = nl() + offset } return res } private fun na2(n: Int, offset: Int = 0): Array { val a = Array(2){IntArray(n)} for (i in 0 until n) { for (e in a) { e[i] = ni() + offset } } return a } private inline fun map(n: Int, f: (Int) -> Int): IntArray { val res = IntArray(n) for (i in 0 until n) { res[i] = f(i) } return res } private inline fun debug(msg: () -> String) { if (isDebug) System.err.println(msg()) } private fun debug(a: LongArray) { debug { a.joinToString(" ") } } private fun debug(a: IntArray) { debug { a.joinToString(" ") } } private fun debug(a: BooleanArray) { debug { a.map { if (it) 1 else 0 }.joinToString("") } } private fun debugDim(A: Array) { if (isDebug) { for (a in A) { debug(a) } } } /** * 勝手にimport消されるのを防ぎたい */ private fun hoge() { min(1, 2) max(1, 2) abs(-10) } } fun main() { val out = java.io.PrintWriter(System.out) Solver(System.`in`, out).solve() out.flush() }