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


#define ll long long
#define vl vector<long long>
#define vll vector<vector<long long>>
ll n, m;
vector<vector<pair<ll, ll>>> edges;

void dfs(ll i, ll t, ll c, vl& comp, vector<vector<pair<ll, ll>>>& graf){
    comp[i] = c;
    for (auto x : graf[i]){
        if (x.second == t && comp[x.first] == -1){
            dfs(x.first, t, c, comp, graf);
        }
    }
}

bool solve(ll t, vector<vector<pair<ll, ll>>>& graf){
    vl comp (n, -1);

    ll c = 0;
    for (ll i = 0; i < n; i++){
        if (comp[i] == -1){
            dfs(i, t ,c, comp, graf);
            c++;
        }
    }

    for (auto x : edges[1-t]){
        if (comp[x.first] == comp[x.second]){
            return true;
        }
    }
    return false;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> n >> m;

    vector<vector<pair<ll, ll>>> graf(n);
    edges.resize(2);
    for (ll i = 0; i < m; i++){
        ll a,b,c;
        cin >> a >> b >> c;

        graf[a].push_back({b, c});
        graf[b].push_back({a, c});

        edges[c].push_back({a, b});
    }

    bool a1, a2;
    a1 = solve(0, graf);
    a2 = solve(1, graf);

    if (a1 || a2){
        cout << "NO\n";
    }
    else{
        cout << "YES\n";
    }
}