package contest200410; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.util.Arrays; import java.util.InputMismatchException; public class D { InputStream is; PrintWriter out; // String INPUT = "3 4 1 2 2 2 3 2 3 2 2 2 1 2"; String INPUT = ""; // 1-3 // /^ // 2>4 // 1-2 // ^/^ // 3-4 void solve() { int n =ni(), m = ni(); int[] from = new int[2*m]; int[] to = new int[2*m]; int[] ws = new int[2*m]; int p = 0; for(int i = 0;i < m;i++){ int x = ni()-1, y = ni()-1, c = ni(); from[p] = x; to[p] = y; ws[p] = c;p++; if(c == 1){ from[p] = y; to[p] = x; ws[p] = c;p++; } } int[][][] g = packWD(n, from, to, ws, p); boolean ans = false; boolean[] ved = new boolean[n]; boolean[] aed = new boolean[n]; for(int i = 0;i < n;i++){ ans |= dfs(i, -1, 0, g, ved, aed); } out.println(ans ? "Yes" : "No"); } public static int[][][] packWD(int n, int[] from, int[] to, int[] w){ return packWD(n, from, to, w, from.length); } public static int[][][] packWD(int n, int[] from, int[] to, int[] w, int sup) { int[][][] g = new int[n][][]; int[] p = new int[n]; for(int i = 0;i < sup;i++)p[from[i]]++; for(int i = 0;i < n;i++)g[i] = new int[p[i]][2]; for(int i = 0;i < sup;i++){ --p[from[i]]; g[from[i]][p[from[i]]][0] = to[i]; g[from[i]][p[from[i]]][1] = w[i]; } return g; } private static boolean dfs(int cur, int pre, int come, int[][][] g, boolean[] ved, boolean[] aed) { ved[cur] = true; int z = 0; for(int[] nex : g[cur]){ if(aed[nex[0]])continue; if(nex[0] == pre){ z++; }else if(ved[nex[0]]){ return true; } if(!ved[nex[0]]){ if(dfs(nex[0], cur, nex[1], g, ved, aed))return true; } } aed[cur] = true; if(z > 0){ if(come == 1){ return z-1 > 0; }else{ return true; } } return false; } public static int[][] packD(int n, int[] from, int[] to){ return packD(n, from, to, from.length);} public static int[][] packD(int n, int[] from, int[] to, int sup) { int[][] g = new int[n][]; int[] p = new int[n]; for(int i = 0;i < sup;i++)p[from[i]]++; for(int i = 0;i < n;i++)g[i] = new int[p[i]]; for(int i = 0;i < sup;i++){ g[from[i]][--p[from[i]]] = to[i]; } return g; } void run() throws Exception { is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes()); out = new PrintWriter(System.out); long s = System.currentTimeMillis(); solve(); out.flush(); if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms"); // Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){ // @Override // public void run() { // long s = System.currentTimeMillis(); // solve(); // out.flush(); // if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms"); // } // }; // t.start(); // t.join(); } public static void main(String[] args) throws Exception { new D().run(); } private byte[] inbuf = new byte[1024]; public int lenbuf = 0, ptrbuf = 0; private int readByte() { if(lenbuf == -1)throw new InputMismatchException(); if(ptrbuf >= lenbuf){ ptrbuf = 0; try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); } if(lenbuf <= 0)return -1; } return inbuf[ptrbuf++]; } private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); } private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; } private double nd() { return Double.parseDouble(ns()); } private char nc() { return (char)skip(); } private String ns() { int b = skip(); StringBuilder sb = new StringBuilder(); while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ') sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } private char[] ns(int n) { char[] buf = new char[n]; int b = skip(), p = 0; while(p < n && !(isSpaceChar(b))){ buf[p++] = (char)b; b = readByte(); } return n == p ? buf : Arrays.copyOf(buf, p); } private int[] na(int n) { int[] a = new int[n]; for(int i = 0;i < n;i++)a[i] = ni(); return a; } private long[] nal(int n) { long[] a = new long[n]; for(int i = 0;i < n;i++)a[i] = nl(); return a; } private char[][] nm(int n, int m) { char[][] map = new char[n][]; for(int i = 0;i < n;i++)map[i] = ns(m); return map; } private int[][] nmi(int n, int m) { int[][] map = new int[n][]; for(int i = 0;i < n;i++)map[i] = na(m); return map; } private int ni() { return (int)nl(); } private long nl() { long num = 0; int b; boolean minus = false; while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')); if(b == '-'){ minus = true; b = readByte(); } while(true){ if(b >= '0' && b <= '9'){ num = num * 10 + (b - '0'); }else{ return minus ? -num : num; } b = readByte(); } } private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); } }