#include <bits/stdc++.h>
using namespace std;
vector<int> R, B;
vector<vector<pair<int,int>>> G;
void find_cp(int v, int c, int i, vector<int>& A){
    A[v] = i;
    for(auto& it : G[v]){
        if (!A[it.first] && it.second == c) {
            find_cp(it.first, c, i, A);
        }
    }
}
int main(){
    int n, m;
    cin >> n >> m;
    int u, v, c;
    G.resize(n); R.resize(n); B.resize(n);
    for(int i = 0; i < m; i++){
        cin >> u >> v >> c;
        G[u].push_back({v, c});
        G[v].push_back({u, c});
    }
    for(int i = 0; i < n; i++){
        if (!R[i])
            find_cp(i, 0, i + 1, R);
        if (!B[i])
            find_cp(i, 1, i + 1, B);
    }
    for(int i = 0; i < n; i++){
        for(auto &it : G[i]){
            if (it.second == 0){
                if (B[i] == B[it.first]) {
                    cout << "NO" << endl;
                    return 0;
                }
            }
            else {
                if (R[i] == R[it.first]){
                    cout << "NO" << endl;
                    return 0;
                }
            }
        }
    }
    cout << "YES" << endl;
}