#include <bits/stdc++.h>
using namespace std;

struct Edge {
	int target;
	int color;
};

enum DiscState {
	FRESH,
	IN_PROGRESS,
	FINISHED
};

struct Tree {
	vector<map<int, Edge>>& edges;
	vector<DiscState>& vertStates;
	vector<int>& predecessors;
	
	set<pair<int, int>> chc;

	Tree(vector<map<int, Edge>>& e, vector<DiscState>& s, vector<int>& p) : edges(e), vertStates(s), predecessors(p) {}

	bool checkCycle(int current, int backTarget) {
		if (chc.count({current, backTarget}) != 0) return true;
		chc.insert({backTarget, current});
		
		int count0 = 0, count1 = 0;

		// process the back-edge
		if (edges[current][backTarget].color == 0)
			++count0;
		else
			++count1;

		for (; current != backTarget; current = predecessors[current]) {
			if (edges[current][predecessors[current]].color == 0)
				++count0;
			else
				++count1;

			if (count0 >= 2 && count1 >= 2)
				return true; // this cycle is peaceful

		}

		if (count0 >= 2 && count1 >= 2)
			return true; // this cycle is peaceful
		if (count0 == 1 || count1 == 1)
			return false;
		
		return true;


	}

	bool dfsVisit(int vert) {
		vertStates[vert] = IN_PROGRESS;
		for (const auto& [_x, edge] : edges[vert]) {
			if (vertStates[edge.target] == FRESH) {
				predecessors[edge.target] = vert;
				bool result = dfsVisit(edge.target);
				if (result == false)
					return false;
			} else if (edge.target != predecessors[vert]) { // if pro kontrolu, ze nejde o immediate predecessora
				// nasli jsme cyklus
				if (checkCycle(vert, edge.target) == false) {
					cout << "cyklus je chaoticky: " << vert << " - " << edge.target << endl;
					return false;
				} else {
					return true;
				}
			}
		}

		return true;
	}
};


int main() {
	int nVert, nEdg;
	cin >> nVert >> nEdg;
	vector<map<int, Edge>> edges(nVert);

	for (int i = 0; i < nEdg; ++i) {
		int u, v, color;
		cin >> u >> v >> color;
		edges[u][v] = Edge{.target=v, .color=color};
		edges[v][u] = Edge{.target=u, .color=color};
		//edges[u].push_back(Edge {.target = v, .color = color});
		//edges[v].push_back(Edge {.target = u, .color = color});
	}

	vector<DiscState> vertStates(nVert, FRESH);
	vector<int> predecessors(nVert, -1);

	Tree t(edges, vertStates, predecessors);

	for (int i = 0; i < nVert; ++i) {
		if (t.vertStates[i] != FRESH) continue;
		auto res = t.dfsVisit(i);
		if (res == false) {
			cout << "NO\n";
			return 0;
		}
	}

	cout << "YES\n";
	return 0;
}