#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#define NMAX 105
#define LMAX 1005
int n,m,sol[NMAX];
struct muchie
{
	int a,b,c;
};
muchie A[LMAX];
void read()
{
	scanf("%d%d",&n,&m);
	int i;
	for (i=1; i<=m; i++)
		scanf("%d%d%d",&A[i].a,&A[i].b,&A[i].c);
}
inline int eval(int tip,int x,int y)
{
	if (tip==0)
		return x | y;
	if (tip==1)
		return x | (!x && !y);
	if (tip==2)
		return y | (!x && !y);
	if (tip==3)
		return !x | !y;
	return 1;
}
inline int exista()
{
	int i;
	for (i=1; i<=n; i++)
		if (sol[i])
			return 1;
	return 0;
}
void solve()
{
	srand(time(0));
	int i,j,found,failed;
	for (i=1; i<=n; i++)
		sol[i]=rand()%2;
	for (i=1; i<=n*20; i++)
	{
		found=1; failed=1;
		for (j=1; j<=m; j++)
			if (!eval(A[j].c,sol[A[j].a],sol[A[j].b]))
			{
				found=0;
				failed=j;
				break ;
			}
		if (found)
		{
			if (exista())
				return ;
		}
		if (rand()%2==0)
			sol[A[failed].a]^=1;
		else
			sol[A[failed].b]^=1;
	}
}
void show()
{
	int i,nr=0;
	for (i=1; i<=n; i++)
		if (sol[i]) 
			nr++;
	printf("%d\n",nr);
	for (i=1; i<=n; i++)
		if (sol[i])
			printf("%d\n",i);
}
int main()
{
	freopen("party.in","r",stdin);
	freopen("party.out","w",stdout);
	read();
	solve();
	show();
	return 0;
}