#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

template <typename T>
ostream& operator<< (ostream& os, const vector<T> & v) {
    os << "[ ";
    for (const T & elem : v) {
        os < elem << " ";
    }
    os << " ]";
    return os;
}

bool bfs(pair<ll, ll> v, ll main_color, vector<ll> & pred, vector<bool> & visited, const vector<vector<pair<ll, ll>>> & graph) {
    queue<pair<ll, ll>> q;
    q.push(v);
    bool inSecondFloor = false;
    while (!q.empty()) {
        ll curr_v = q.front().first;
        ll curr_floor = q.front().second;
        //cout << "curr_v: " << curr_v << "  curr_floor: " << curr_floor << " " << inSecondFloor <<endl;
        q.pop();

        if(inSecondFloor == true)
            curr_floor = 1;

        for (auto & neig : graph[curr_v]) {
            ll neig_v = neig.first;
            ll edge_color = neig.second;

            if (pred[curr_v] == neig_v)
                continue;

            if(inSecondFloor == true)
                curr_floor = 1;

            if (curr_floor == 0) {
                if (edge_color == main_color && !visited[neig_v]) {
                    visited[neig_v] = true;
                    pred[neig_v] = curr_v;
                    q.push({neig_v, curr_floor});

                } else if (edge_color != main_color && !inSecondFloor) {
                    if (visited[neig_v]) {
                        //cout << "curr: " << curr_v << "neigh: " << neig_v << endl;
                        return true;
                    }
                    inSecondFloor = true;
                    visited[neig_v] = true;
                    pred[neig_v] = curr_v;
                    q.push({neig_v, 1});
                    curr_floor = 1;
                }

            } else if (curr_floor == 1) {
                if (edge_color != main_color)
                    continue;
                

                if (visited[neig_v]) {
                    //cout << "curr: " << curr_v << "neigh: " << neig_v << endl;
                    return true;
                }

                visited[neig_v] = true;
                q.push({neig_v, 1});
                pred[neig_v] = curr_v;
                
            }
        }
    }
    return false;
}

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

    vector<vector<pair<ll, ll>>> graph(n);
    for (ll i = 0; i < m; ++i) {
        ll u, v, c;
        cin >> u >> v >> c;
        graph[u].push_back({v, c});
        graph[v].push_back({u, c});
    }

    // RED - 0
    // BLUE - 1

    vector<ll> pred(n, -1);     // pred[v][copy]
    vector<bool> visited(n, false);
    bool has_red_cycle_with_one_blue = false;
    for (ll i = 0; i < n; ++i) {
        if (!visited[i]) {
            pred[i] = i;
            visited[i] = true;
            has_red_cycle_with_one_blue |= bfs({i, 0}, 0, pred, visited, graph);
        }
    }

    //if(has_red_cycle_with_one_blue)
    //    cout << "true" << endl;
    //else
    //    cout << "false" << endl;
    //cout << "------" << endl;

    pred = vector<ll> (n, -1);
    visited = vector<bool>(n, false);
    bool has_blue_cycle_with_one_red = false;
    for (ll i = 0; i < n; ++i) {
        if (!visited[i]) {
            pred[i] = i;
            visited[i] = true;
            has_blue_cycle_with_one_red |= bfs({i, 0}, 1, pred, visited, graph);
        }
    }
    //if(has_blue_cycle_with_one_red)
    //    cout << "true" << endl;
    //else
    //    cout << "false" << endl;

    if (has_red_cycle_with_one_blue || has_blue_cycle_with_one_red)
        cout << "NO" << endl;
    else
        cout << "YES" << endl;
}

int main() {
    cin.tie(0);
    cout.tie(0);
    cin.exceptions(ios::failbit);
    ios::sync_with_stdio(false);
    ll t = 1;
    // cin >> t; // potential comment
    while (t--) {
        test_case();
    }
    return 0;
}