#include <bits/stdc++.h>
#include <cassert>
using namespace std;
using ll = long long;
// #define int ll

struct edge {
    int to, clr;
};

bool cycle(int n, int m, vector<vector<edge>> & adj) {
    // clr 0 are bfsable
    vector<int> comp(n, -1);
    int counter = 0;
    for (int i = 0; i < n; i++) {
        if (comp[i] != -1) {
            continue;
        }
        queue<int> q;
        q.push(i);
        comp[i] = counter++;
        // prednaskovy BFS algoritmus (korektni)
        while (!q.empty()) {
            auto curr = q.front(); q.pop();
            for (auto [to, clr] : adj[curr]) {
                if (clr != 0) continue;
                if (comp[to] == comp[i]) continue; // seen
                assert(comp[to] == -1);
                comp[to] = comp[i];
                q.push(to);
            }
        }
    }

    for (int i = 0; i < n; i++) {
        for (auto [to, clr] : adj[i]) {
            if (clr == 0) continue;
            assert(comp[i] != -1);
            assert(comp[to] != -1);
            if (comp[i] == comp[to]) {
                return true;
            }
        }
    }
    return false;
}

signed main() {
    int n, m; cin >> n >> m;
    vector<vector<edge>> adj(n);
    for (int i = 0; i < m; i++) {
        int u, v, clr; cin >> u >> v >> clr;
        adj[u].push_back({v, clr});
        adj[v].push_back({u, clr});
    }
    bool res = cycle(n, m, adj);
    if (res) {
        cout << "NO" << endl;
        return 0;
    }
    for (int i = 0; i < n; i++) {
        for (auto & edg : adj[i]) {
            edg.clr = 1 - edg.clr;
        }
    }
    res = cycle(n, m, adj);
    if (res) {
        cout << "NO" << endl;
        return 0;
    }
    cout << "YES" << endl;
    return 0;
}