#include <bits/stdc++.h>

using namespace std;
using ll = long long;

using edge = pair<ll, ll>;

void buildComp(map<ll, vector<edge>>& adj,
               vector<ll>& comp, ll color) {
    ll n = comp.size();

    ll counter = 0;

    for (ll i = 0; i < n; ++i) {
        if (comp[i] != -1)
            continue;

        queue<ll> q{};
        q.push(i);
        while (!q.empty()) {
            ll top = q.front();
            q.pop();
            comp[top] = counter;
            for (auto& [ to, c ] : adj[top]) {
                if (c != color) continue;
                if (comp[to] != -1) continue;
                q.push(to);
            }
        }

        ++counter;
    }
}

void process() {
    ll m, n;
    cin >> n >> m;

    map<ll, vector<edge>> adj{};
    for (ll i = 0; i < m; ++i) {
        ll u, v, c;
        cin >> u >> v >> c;
        adj[u].emplace_back(v, c);
        adj[v].emplace_back(u, c);
    }

    vector<ll> comp_zero(n, -1);
    buildComp(adj, comp_zero, 0);

    vector<ll> comp_one(n, -1);
    buildComp(adj, comp_one, 1);

    for (auto& [ u, edge ] : adj) {
        for (auto& [ v, c ] : edge) {
            if (c == 0) {
                ll fc = comp_one[u];
                ll sc = comp_one[v];
                if (fc == -1 || sc == -1) {
                    continue;
                }
                if (fc != sc) {
                    continue;
                }
                cout << "NO\n";
                return;
            } else {
                ll fc = comp_zero[u];
                ll sc = comp_zero[v];
                if (fc == -1 || sc == -1) {
                    continue;
                }
                if (fc != sc) {
                    continue;
                }
                cout << "NO\n";
                return;
            }
        }
    }

    cout << "YES\n";
}

int main() {
    std::ios::sync_with_stdio(false);
    process();
    cout.flush();
    return 0;
}