#include <cstdio>
#include <stdlib.h>
#include <ctime>
#include <vector>
using namespace std;

#define Nmax 105

struct relatie {int x, y, tip;} aux;
int n, m, x, y, tip, i, nr, p, ok;
int sol[Nmax];
vector <relatie> R;

int main () {
	
	srand (time (0));
	freopen ("party.in", "r", stdin);
	freopen ("party.out", "w", stdout);
	
	scanf ("%d %d", &n, &m);
	for (i = 1; i <= n; i++)
		sol[i] = rand () %2;
	
	for (i = 1; i <= m; i++) {
		scanf ("%d %d %d", &aux.x, &aux.y, &aux.tip);
		R.push_back (aux);
	}
	
	while (!ok) {
		
		ok = 1;
		for (i = 0; i < m; i++) {
			aux = R[i];
			if (aux.tip == 0) {
				if (!sol[aux.x] && !sol[aux.y]) {
					p = i;
					ok = 0;
					break;
				}
			}
			
			else {
				if (aux.tip == 1) {
					if (!sol[aux.x] && sol[aux.y]) {
						p = i;
						ok = 0;
						break;
					}
				}
				
				else {
					if (aux.tip == 2) {
						if (sol[aux.x] && !sol[aux.y]) {
							p = i;
							ok = 0;
							break;
						}
					}
					
					else {
						if (sol[aux.x] && sol[aux.y]) {
							p = i;
							ok = 0;
							break;
						}
					}
				}
			}
		}
		
		if (!ok ) {
			aux = R[p];
			if (rand () % 2)
				sol[aux.x]^= 1;
			else
				sol[aux.y]^= 1;
			
			//R[p] = aux;
		}
	}
	
	for (i = 1; i <= n; i++)
		nr+= sol[i];
	
	printf ("%d\n", nr);
	for (i = 1; i <= n; i++) 
		if (sol[i]) printf ("%d\n", i);
	
	return 0;
}