#include <vector>
#include <cstdio>
#include <unordered_map>

using namespace std;

int n, m;
vector<vector<pair<int, int>>> g;

vector<int> state, tin, tout, parent;
int r, b, T;
int start;
bool dfs(int u) {
	state[u] = 1; tin[u] = T++;
	for (auto [v, c] : g[u]) {
		if (state[v] == 0) {
			if (c) r += 1; else b += 1;
			//printf("%d: r=%d b=%d\n", v, r, b);
			if (r >= 2 && b >= 2) { if (c) r -= 1; else b -= 1; return true; } // pruning
			parent[v] = u; if (!dfs(v)) return false;
			if (c) r -= 1; else b -= 1; 
		}
		else if (state[v] == 1 && v == start) {
			if (c) r += 1; else b += 1;
			if (!(r == 0 || b == 0 || (r >= 2 && b >= 2))) return false;
			if (c) r -= 1; else b -= 1; 
		}
	} 
	state[u] = 2; tout[u] = T++;
	return true;
}
bool runDfs(int u) {
	state.assign(n, 0); tin.assign(n, 0); tout.assign(n, 0);
	parent.assign(n, -1);
	r = 0; b = 0; T = 0;
	start = u;
	return dfs(u);
}

int main() {
	scanf("%d %d", &n, &m);
	g = vector<vector<pair<int, int>>>(n);
	
	for (int i = 0; i < m; ++i) {
		int u, v, c;
		scanf("%d %d %d", &u, &v, &c);
		g[u].push_back(pair<int, int>{v, c});
		g[v].push_back(pair<int, int>{u, c});
	}

	bool correct = true;
	for (int u = 0; u < n; u++) {
		if (!runDfs(u)) {correct = false; break;}
	}
	if (correct) {
		printf("YES\n");
	} else {printf("NO\n");}

	return 0;
}