#include <bits/stdc++.h>

using namespace std;

using ll = long long;
#define int long long

const int N = 300005;
vector<pair<int, int>> G[N];
bool vis[N];
int tin[N];
int comp[N], CO = 1;
bool dfs(int v, int cur, int par = -1) {
    vis[v] = true;
    comp[v] = CO;
    for (auto [to, col] : G[v]) {
        if (to == par) {
            continue;
        }
        // cout<<v<<" "<<to<<" "<<vis[to]<<" "<<comp[to]<<endl;
        if (vis[to]) {
            if (comp[to] != comp[v]) {
                continue;
            }
            if (col == (cur ^ 1)) {
                // cout<<comp[v]<<" "<<comp[to]<<" "<<v<<" "<<to<<" "<<col<<" "<<cur<<endl;
                return false;
            }
        } else {
            if (col == cur) {
                if (!dfs(to, cur, v)) {
                    return false;
                }
            }
        }
    }
    return true;
}


void solve(){
    int n,m ;
    cin >> n  >> m;
    for (int i = 0; i < m; ++i) {
        int u, v, c;
        cin >> u >> v >> c;
        G[u].push_back({v, c});
        G[v].push_back({u, c});
    }
    for (int i = 0; i < n; ++i) {
        vis[i] = false;
        comp[i] = -1;
        CO = 1;
    }
    for (int i = 0; i < n; ++i) {
        if (!vis[i]) {
            if (!dfs(i, 0)) {
                cout << "NO\n";
                return;
            }
            CO++;
        }
    }
    
    for (int i = 0; i < n; ++i) {
        vis[i] = false;
        comp[i] = -1;
        CO = 1;
    }
    for (int i = 0; i < n; ++i) {
        if (!vis[i]) {
            if (!dfs(i, 1)) {
                cout << "NO\n";
                return;
            }
            CO++;
        }
    }
    cout << "YES\n";
}

int32_t main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int t=1;
    // cin>>t;
    for(int _=1;_<=t;_++){
        solve();
    }
}