#include <iostream>
#include <vector>

using namespace std;

#define RED 1
#define BLUE 0

struct Node{
    Node() {
        connections.reserve(100);
        colors.reserve(100);
    }
    vector<int> connections;
    vector<bool> colors;
};

vector<Node> nodes;
vector<int> nodesOneColor;

vector<bool> visited;

bool loop(int start, int cur, int bc, int rc, int depth) {
    //cout << "NODE: " << cur << '\n';
    if (visited[cur]) {
        if (cur == start) {
            if (rc != 0 && bc != 0) {
                if (rc == 1 || bc == 1) {
                    return false;
                }
            }
        }
        return true;
    }

    if (depth <= 0) {
        return true;
    }

    if (rc > 1 && bc > 1) {
        return true;
    }

    Node& n = nodes[cur];
    int firstI = 0;
    for (int i = 0; i < n.connections.size(); i++) {
        if (n.connections[i] == start) {
            firstI = i;
            break;
        }
    }
    {
        int i = firstI;
        int edge = n.connections[i];
        bool color = n.colors[i];
        //cout << "EDGE: " << cur << ' ' << edge << " COLOR: " << color << '\n';
        if (color == 1) {
            ++rc;
        } else {
            ++bc;
        }

        visited[cur] = true;
        if (!loop(start, edge, bc, rc, depth - 1)) {
            visited[cur] = false;
            return false;
        }
        visited[cur] = false;

        if (color == 1) {
            --rc;
        } else {
            --bc;
        }
    }
    for (int i = 0; i < n.connections.size(); i++) {
        if (firstI == i) {
            continue;
        }
        int edge = n.connections[i];
        bool color = n.colors[i];
        //cout << "EDGE: " << cur << ' ' << edge << " COLOR: " << color << '\n';
        if (color == 1) {
            ++rc;
        } else {
            ++bc;
        }

        visited[cur] = true;
        if (!loop(start, edge, bc, rc, depth - 1)) {
            visited[cur] = false;
            return false;
        }
        visited[cur] = false;

        if (color == 1) {
            --rc;
        } else {
            --bc;
        }
    }
    return true;
}

int cN, cE;

bool isOk() {
    for (int d = max(cN / 2, 3); d <= cN; d = max(cN, d + 3)) {
        for (int i = 0; i < nodesOneColor.size(); ++i) {
            //cout << "ROUND: " << i << '\n';
            if (!loop(nodesOneColor[i], nodesOneColor[i], 0, 0, d)) {
                return false;
            }
        }
        if (d == cN) {
            d++;
        }
    }
    return true;
}

int main() {
    cin >> cN >> cE;

    nodes.reserve(cN);

    for (int i = 0; i < cN; ++i){
        nodes.emplace_back();
    }

    visited.resize(cN);
    visited.clear();

    for (int i = 0; i < cN; i++) {
        int x1, x2, col;
        cin >> x1 >> x2 >> col;
        {
            Node &n = nodes[x1];
            n.colors.push_back(col);
            n.connections.push_back(x2);
        }
        {
            Node &n = nodes[x2];
            n.colors.push_back(col);
            n.connections.push_back(x1);
        }
        if (col == 1) {
            nodesOneColor.push_back(x1);
            nodesOneColor.push_back(x2);
        }
    }

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

    return 0;
}