import java.util.*;

/*
3 3
0 1 1
0 2 1
1 2 0

NO

4 4
0 1 1
1 2 1
2 3 0
3 0 0

YES

3 3
0 1 0
0 2 0
1 2 1

NO
 */
public class Nightmare {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt(); // vertexes
        int m = in.nextInt(); // edges

        Map<Integer, List<Integer>> redGraph = new HashMap<>();
        Map<Integer, List<Integer>> blueGraph = new HashMap<>();
        for (int i = 0; i < m; i++) {
            int from = in.nextInt();
            int to = in.nextInt();
            int color = in.nextInt();
            if(color == 0) {
                addEdge(redGraph, from, to);
                addEdge(redGraph, to, from);
            } else {
                addEdge(blueGraph,from, to);
                addEdge(blueGraph,to, from);
            }
        }

        boolean found = search(redGraph, blueGraph) || search(blueGraph, redGraph);

        System.out.println(found?"NO":"YES");
    }

    private static boolean search(Map<Integer, List<Integer>> redGraph, Map<Integer, List<Integer>> blueGraph) {
        for (Map.Entry<Integer, List<Integer>> edge : redGraph.entrySet()) {
            int from = edge.getKey();
            for(Integer to : edge.getValue()) {
                if( dfs(blueGraph, to, from, new HashSet<>())) {
                    return true;
                }
            }
        }
        return false;
    }

    private static boolean dfs(Map<Integer, List<Integer>> blueGraph, int from, int to, Set<Integer> visited) {
        if(to==from) {
            return true;
        }
        if(blueGraph.containsKey(from)) {
            visited.add(from);
            for (int current : blueGraph.get(from)) {
                if (!visited.contains(current)) {
                    if (dfs(blueGraph, current, to, visited)) {
                        return true;
                    }
                }
            }
            visited.remove(from);
        }
        return false;
    }

    private static void addEdge(Map<Integer, List<Integer>> graph, int from, int to) {
        graph.putIfAbsent(from, new ArrayList<>());
        graph.get(from).add(to);
    }
}