#include <stdio.h>
#include <stdlib.h>
#define MAXN 1024

struct muchie{
	int x,y,caz;
};

int fol[MAXN];
muchie a[MAXN];
int nr,i,n,m,aux,ok;

bool corect(int i)
{
	if (a[i].caz == 0)
		return (fol[a[i].x] || fol[a[i].y]);
	if (a[i].caz == 3)
		return ((!fol[a[i].x]) || (!fol[a[i].y]));
	return (fol[a[i].x] || (!fol[a[i].y]));
}

int main()
{
	freopen("party.in","r",stdin);
	freopen("party.out","w",stdout);
	scanf("%d %d",&n,&m);
	for (i=1; i<=m; i++){
		scanf("%d %d %d",&a[i].x,&a[i].y,&a[i].caz);
		if (a[i].caz==2) {
			aux = a[i].x;
			a[i].x = a[i].y;
			a[i].y = aux;
			a[i].caz = 1;
		}
	}
	for (i=1; i<=n; i++)
		fol[i]=1;
	for (ok=0; !ok; ){
		ok = 1;
		for (i=1; i<=m; i++)
			if (!corect(i)) {
				ok=0;
				aux = rand()%2;
				if (aux ==0) 
					fol[a[i].x] ^=1;
				else
					fol[a[i].y] ^=1;
			}
	}
	for (i=1; i<=n; i++)
		nr +=fol[i];
	printf("%d\n",nr);
	for (i=1; i<=n; i++)
		if (fol[i]) 
			printf("%d\n",i);
	return 0;
}