#include <bits/stdc++.h>

using namespace std;

using ll = long long;
#define all(x) begin(x), end(x)
#define rep(i,a,b) for (auto i = a; i < (b); ++i)
#define vi vector<int>
#define pii pair<int,int>

#define W(x) cerr << #x << ": " << (x) << "\n";

struct UF {
	vi p;
	UF(int n) : p(n, -1) {}
	int get(int v) { return p[v] < 0 ? v : (p[v] = get(p[v])); }
	bool merge(int a, int b) {
		a = get(a);
		b = get(b);
		if (a == b)
			return false;
		
		if (p[a] > p[b])
			swap(a,b);
		p[a] += p[b];
		p[b] = a;
		return true;
	}
};

struct edge {
	int a, b;
	int c;
};

vector<edge> egs;

int n, m;

bool check() {
	UF uf(n);
	rep(i,egs.begin(),egs.end()) {
		if(i->c){
			uf.merge(i->a, i->b);
		}
	}
	rep(i,egs.begin(),egs.end()) {
		if(i->c == 0){
			if(uf.get(i->a) == uf.get(i->b)){
				return false;
			}
		}
	}
	return true;
}

int main () {
	cin.tie(0)->sync_with_stdio(0);

	cin >> n >> m;

	egs.reserve(m);

	for (int i = 0; i < m; i++){
		int a, b, c;
		cin >> a >> b >> c;
		egs.push_back({a, b, c});
	}

	bool res = check();
	rep(i,egs.begin(),egs.end()) {
		i->c ^= 1; 
	}
	res = res && check();

	cout << (res? "YES" : "NO") << "\n";

	return 0;
}