#include<cstdio>
#include<cstdlib>
int n,m,i,nr,x,a[1001][3],v[101];
inline int ver(int i)
{
	switch(a[i][2])
	{
	case 0:
		return v[a[i][0]] || v[a[i][1]];
		break;
	case 1:
		return v[a[i][0]] || !v[a[i][1]];
		break;
	case 2:
		return v[a[i][1]] || !v[a[i][0]];
		break;
	case 3:
		return v[a[i][0]]+v[a[i][1]]!=2;
		break;
	}
	return 1;
}
inline void correct(int i)
{
	x=rand()%2;
	v[a[i][x]]=!v[a[i][x]];
}
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][0],&a[i][1],&a[i][2]);
	}
	for(i=1;i<=n;i++) v[i]=1;
	while(1)
	{
		for(i=1;i<=m;i++)
			if(!ver(i)) 
			{
				correct(i);
				break;
			}
		if(i==m+1) break;
	}
	for(i=1;i<=n;i++)
		if(v[i]) nr++;
	printf("%d\n",nr);
	for(i=1;i<=n;i++)
		if(v[i]) printf("%d\n",i);
	fclose(stdout);
	return 0;
}