#include <bits/stdc++.h>
using namespace std;
#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define fo(i, n) rep(i, 0, n)
#define all(x) std::begin(x), std::end(x)
#define sz(x) int((x).size())
#define F first
#define S second
#define MP make_pair
#define PB push_back
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef vector<ll> vll;
typedef pair<ll, ll> pll;
typedef vector<vll> vvll;
typedef vector<pll> vpll;
typedef vector<double> vd;
typedef pair<double, double> pdd;
typedef vector<vd> vvd;
typedef vector<pdd> vpdd;

struct node
{
    array<vi, 2> edges;
    array<int, 2> comps = {{-1, -1}};
};

vector<node> nodes;
array<vpii, 2> edges;

signed main()
{
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.badbit | cin.failbit);

    ll n, m;
    cin >> n >> m;
    nodes = vector<node>(n);

    fo(___, m)
    {
        ll u, v, c;
        cin >> u >> v >> c;
        nodes[u].edges[c].push_back(v);
        nodes[v].edges[c].push_back(u);
        edges[c].push_back(MP(u, v));
    }

    fo(c, 2)
    {
        ll comp_num = 0;
        deque<int> queue;

        fo(start, n)
        {
            if (nodes[start].comps[c] >= 0)
                continue;

            queue.push_back(start);
            nodes[start].comps[c] = comp_num;

            while (!queue.empty())
            {
                int u = queue.front();
                queue.pop_front();

                for (int v : nodes[u].edges[c])
                {
                    if (nodes[v].comps[c] >= 0)
                        continue;

                    queue.push_back(v);
                    nodes[v].comps[c] = comp_num;
                }
            }

            comp_num++;
        }
    }

    bool ok = true;

    fo(c, 2)
    {
        for (auto [u, v] : edges[c])
        {
            if (nodes[u].comps[!c] == nodes[v].comps[!c])
                ok = false;
        }
    }

    if (ok)
        cout << "YES\n";
    else
        cout << "NO\n";
}