#include <bits/stdc++.h>

using namespace std;
using ll = long long;

using edge = pair<ll, ll>;

void compute_components(map<ll, vector<edge>> &adjacent, vector<ll> &components, ll color) {
    for (ll i = 0; i < components.size(); i++) {
        if (components[i] != -1) continue;

        queue<ll> q;
        vector<bool> visited(components.size());

        q.push(i);
        visited[i] = true;

        while (!q.empty()) {
            ll vertex = q.front();
            q.pop();
            components[vertex] = i;
            if (!adjacent.count(vertex)) continue;
            for (edge adjacentEdge : adjacent[vertex]) {
                if (components[adjacentEdge.first] != -1) continue;
                if (visited[adjacentEdge.first]) continue;
                if (adjacentEdge.second != color) continue;

                q.push(adjacentEdge.first);
                visited[adjacentEdge.first] = true;
            }
        }
    }
}

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

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

    vector<ll> components0(n);
    std::fill(components0.begin(), components0.end(), -1);
    vector<ll> components1(n);
    std::fill(components1.begin(), components1.end(), -1);
    compute_components(adjacent, components0, 0);
    compute_components(adjacent, components1, 1);

    ////////////

    for (ll i = 0; i < n; i++) {
        if (!adjacent.count(i)) continue;

        for (edge adjacentEdge : adjacent[i]) {
            if (components0[i] == components0[adjacentEdge.first] && adjacentEdge.second == 1) {
                cout << "NO" << endl;
                return;
            }
            if (components1[i] == components1[adjacentEdge.first] && adjacentEdge.second == 0) {
                cout << "NO" << endl;
                return;
            }
        }
    }

    cout << "YES" << endl;
    return;
}

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