#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using vi = vector<int>;
using pi = pair <int, int>;
using vvi = vector<vi>;

void solve ()
{
    int n, m;
    cin >> n >> m;
    vvi gr[2] = {vvi(n), vvi(n)};
    for (int i = 0; i < m; ++i)
    {
        int u, v, c;
        cin >> u >> v >> c;
        gr[c][u].push_back(v);
        gr[c][v].push_back(u);
    }

    vi comp[2] = {vi(n), vi(n)};

    auto Dfs = [&](auto&& self, int v, int c, int tag)
    {
        if (comp[c][v] == tag)
            return;
        comp[c][v] = tag;
        for (int u : gr[c][v])
            self(self, u, c, tag);
    };

    for (int c = 0; c < 2; ++c)
    {
        int t = 1;
        for (int i = 0; i < n; ++i)
        {
            if (comp[c][i])
                continue;
            Dfs(Dfs, i, c, t);
            ++t;
        }
    }

    bool good = true;
    for (int c = 0; c < 2 && good; ++c)
    {
        for (int v = 0; v < n && good; ++v)
        {
            for (int u : gr[c][v])
            {
                assert(comp[1 - c][u] != 0);
                assert(comp[1 - c][v] != 0);
                if (comp[1 - c][u] == comp[1 - c][v])
                {
                    good = false;
                    break;
                }
            }
        }
    }
    cout << (good ? "YES\n" : "NO\n");
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    solve();
    return 0;
}