#include using namespace std; #define DEBUG(x) cerr<<#x<<": "< #define vl vector #define vii vector< vector > #define vll vector< vector > #define vs vector #define pii pair #define pis pair #define psi pair #define pll pair template pair operator+(const pair &s, const pair &t) { return pair(s.first + t.first, s.second + t.second); } template pair operator-(const pair &s, const pair &t) { return pair(s.first - t.first, s.second - t.second); } template ostream& operator<<(ostream& os, pair p) { os << "(" << p.first << ", " << p.second << ")"; return os; } #define X first #define Y second #define rep(i,n) for(int i=0;i<(int)(n);i++) #define rep1(i,n) for(int i=1;i<=(int)(n);i++) #define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--) #define rrep1(i,n) for(int i=(int)(n);i>0;i--) #define REP(i,a,b) for(int i=a;i bool chmax(T &a, const T &b) { if (a bool chmin(T &a, const T &b) { if (a>b) { a = b; return 1; } return 0; } #define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end()); const ll inf = 1000000001; const ll INF = (ll)1e18 + 1; const long double pi = 3.1415926535897932384626433832795028841971L; #define Sp(p) cout<>> G(3); vii visited; bool dfs(int now, int from, int state, int turn) { visited[now][state] = turn; vi idx = {0, 1}; for (int i: idx) { int nstate; if (i == 0) nstate = state; else nstate = i; for (pii v: G[i][now]) { if (v.second == from) continue; if (visited[v.first][nstate] == turn) return true; if (visited[v.first][nstate] == 0) { if (dfs(v.first, v.second, nstate, turn)) return true; } } } visited[now][state] = -1; return false; } signed main() { int n, m; cin >> n >> m; rep (i, 2) { G[i].resize(n); } visited.resize(n); rep (i, n) { visited[i].resize(2); rep (j, 2) visited[i][j] = 0; } rep (i, m) { int u, v, t; cin >> u >> v >> t; u--; v--; if (t == 1) { G[0][u].push_back(pii(v, i)); G[0][v].push_back(pii(u, i)); } else { G[1][u].push_back(pii(v, i)); } } // rep (i, 3) { // DEBUG(i); // rep (u, n) { // cout << u << ": "; // for (pii v: G[i][u]) { // cout << v << " "; // } // cout << endl; // } // } int turn = 1; rep (i, n) { if (visited[i][0] != 0) continue; if (dfs(i, -1, 0, turn)) { //DEBUG_MAT(visited); cout << "Yes" << endl; return 0; } //DEBUG_MAT(visited); turn++; } cout << "No" << endl; }