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

vector<vector<pair<int, int>>> AL;
vector<pair<int, int>> colors;
vector<int> visited;

int res = 1;

int DFS(int u, int l) {
    visited[u] = 1;
    for (auto [v, c] : AL[u]) if (v != l) {
        //printf("%d %d | %d %d\n", u, v, colors[l].first, colors[l].second);
        if (visited[v] == 1) {
            int a = 0, b = 0;
            // printf("Cycle: ");
            for (int i = v; colors[i].first != -1; i = colors[i].first) {
                if (colors[i].second == 0) a++;
                else b++;
                // printf("[%d %d %d] ", i, colors[i].first, colors[i].second);
            }
            // printf("[%d %d %d] ", u, colors[u].first, colors[u].second);
            //printf("\n");
            if (c == 0) a++;
            else b++;

            //printf("colors: %d %d\n", a, b);


            if (!(a == 0 || b == 0 || (a >= 2 && b >= 2))) return 0;

        } else {
            colors[u] = {v, c};
            if (!DFS(v, u)) return 0;
            colors[u] = {-1, -1};
        }
    }
    return 1;
}

int main() {
    int n, m;
    scanf("%d %d", &n, &m);

    AL.assign(n, vector<pair<int, int>>());

    for (int i = 0; i < m; i++) {
        int u, v, c;
        scanf("%d %d %d", &u, &v, &c);

        AL[u].push_back({v, c});
        AL[v].push_back({u, c});
    }

    // for (int i = 0; i < n; ++i) {
    //     printf("%d: ", i);
    //     for (auto &[v, c] : AL[i]) {
    //         printf("[%d %d] ", v, c);
    //     }
    //     printf("\n");
    // }

    colors.assign(n, {-1, -1});
    visited.assign(n, 0);

    for (int i = 0; i < n && res; ++i) if (visited[i] == 0) {
        res &= DFS(i, 0);
    }

    if (res) printf("YES\n");
    else printf("NO\n");
    



    return 0;
}