import std.conv, std.functional, std.range, std.stdio, std.string; import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons; import core.bitop; class EOFException : Throwable { this() { super("EOF"); } } string[] tokens; string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; } int readInt() { return readToken.to!int; } long readLong() { return readToken.to!long; } real readReal() { return readToken.to!real; } bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } } bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } } int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; } int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); } int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); } int root(int[] uf, int u) { return (uf[u] < 0) ? u : (uf[u] = uf.root(uf[u])); } bool connect(int[] uf, int u, int v) { u = uf.root(u); v = uf.root(v); if (u == v) return false; if (uf[u] > uf[v]) swap(u, v); uf[u] += uf[v]; uf[v] = u; return true; } Tuple!(int, int[]) scc(in int[][][] graph) { const n = cast(int)(graph[0].length); int compN; auto compIds = new int[n]; int[] us; void dfs(int s, int u, int a, int b) { if (compIds[u] == a) { compIds[u] = b; foreach (v; graph[s][u]) { dfs(s, v, a, b); } if (s == 0) { us ~= u; } } } foreach (u; 0 .. n) { dfs(0, u, 0, -1); } foreach_reverse (u; us) { if (compIds[u] == -1) { dfs(1, u, -1, compN); ++compN; } } return tuple(compN, compIds); } void main() { try { for (; ; ) { const N = readInt(); const M = readInt(); auto A = new int[M]; auto B = new int[M]; auto C = new int[M]; foreach (i; 0 .. M) { A[i] = readInt() - 1; B[i] = readInt() - 1; C[i] = readInt(); } auto graph = new int[][][](2, N); void ae(int u, int v) { graph[0][u] ~= v; graph[1][v] ~= u; } foreach (i; 0 .. M) { if (C[i] == 1) { ae(A[i], B[i]); ae(B[i], A[i]); } else { ae(A[i], B[i]); } } const res = scc(graph); bool ans; foreach (i; 0 .. M) { if (C[i] == 2) { if (res[1][A[i]] == res[1][B[i]]) { ans = true; } } } auto uf = new int[N]; uf[] = -1; foreach (i; 0 .. M) { if (C[i] == 1) { if (!uf.connect(A[i], B[i])) { ans = true; } } } writeln(ans ? "Yes" : "No"); } } catch (EOFException e) { } }