#include <bits/stdc++.h>

#define rep(i,a,b) for(int i = a; i < (b); ++i)
#define sz(x) (int)(x).size()

using namespace std;

using ll = long long;
using pi = pair<int, int>;
using vi = vector<int>;

struct Node {
	int label;
	vi succ;
};

void dfs(vector<Node>& g, int u, int c) {
	Node& n = g[u];
	if (n.label == c) return;
	n.label = c;
	for (auto v : n.succ) {
		dfs(g, v, c);
	}
}

using Graph = vector<Node>;

bool find(Graph& a, Graph& b) {
	rep(u, 0, sz(b)) {
		for(auto v : b[u].succ) {
			if (u > v) continue;
			if (a[u].label == a[v].label) return true;
		}
	}
	return false;
}

void solve() {
	int n, m;
	cin >> n >> m;
	vector<Node> red(n);
	vector<Node> blue(n);
	rep(i, 0, m) {
		int u, v, c;
		cin >> u >> v >> c;
		auto& g = c ? blue : red;
		g[u].succ.push_back(v);
		g[v].succ.push_back(u);
	}

		for (int i = 0; i < sz(red); ++i) {
			if (red[i].label == 0) dfs(red, i, i + 1);
		}
		for (int i = 0; i < sz(blue); ++i) {
			if (blue[i].label == 0) dfs(blue, i, i + 1);
		}

	cout << (!find(red, blue) && !find(blue, red) ? "YES\n" : "NO\n");
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	solve();
}