#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define Dim 101

struct vector
{
	int x,y,z;
}v[Dim*10];

char use[Dim];

int main()
{
	int i,pos,N,M,end;

	freopen("party.in","r",stdin);

	scanf("%d%d",&N,&M);
	for(i=1;i<=M;i++)
	{
		scanf("%d%d%d",&v[i].x,&v[i].y,&v[i].z);
		if(v[i].z==2)
		{
			v[i].z=v[i].x;
			v[i].x=v[i].y;
			v[i].y=v[i].z;
			v[i].z=1;
		}
	}

	srand(time(NULL));
	for(i=1;i<=N;i++) use[i]=rand()%2;

	end=0;
	while(!end)
	{
		end=1;
		pos=rand()%M+1;

		for(i=pos;i<=M;i++)
			if(v[i].z==0)
			{
				if(use[v[i].x]==0&&use[v[i].y]==0)
				{
					if(rand()%2) use[v[i].x]=1-use[v[i].x];
					else use[v[i].x]=1-use[v[i].x];
					end=0;
					break;
				}
			}
			else
			if(v[i].z==1)
			{
				if(use[v[i].x]==0&&use[v[i].y]!=0)
				{
					if(rand()%2) use[v[i].x]=1-use[v[i].x];
					else use[v[i].x]=1-use[v[i].x];
					end=0;
					break;
				}
			}
			else
			if(v[i].z==3)
			{
				if(use[v[i].x]==1&&use[v[i].y]==1)
				{
					if(rand()%2) use[v[i].x]=1-use[v[i].x];
					else use[v[i].x]=1-use[v[i].x];
					end=0;
					break;
				}
			}

		if(end)
			for(i=1;i<=pos;i++)
				if(v[i].z==3)
				{
					if(use[v[i].x]==1&&use[v[i].y]==1)
					{
						if(rand()%2) use[v[i].x]=1-use[v[i].x];
						else use[v[i].x]=1-use[v[i].x];
						end=0;
						break;
					}
				}
				else
				if(v[i].z==0)
				{
					if(use[v[i].x]==0&&use[v[i].y]==0)
					{
						if(rand()%2) use[v[i].x]=1-use[v[i].x];
						else use[v[i].x]=1-use[v[i].x];
						end=0;
						break;
					}
				}
				else
				if(v[i].z==1)
				{
					if(use[v[i].x]==0&&use[v[i].y]!=0)
					{
						if(rand()%2) use[v[i].x]=1-use[v[i].x];
						else use[v[i].x]=1-use[v[i].x];
						end=0;
						break;
					}
				}
	}

	freopen("party.out","w",stdout);

	use[0]=0;
	for(i=1;i<=N;i++) use[0]+=use[i];
	printf("%d\n",use[0]);
	for(i=1;i<=N;i++)
		if(use[i]) printf("%d\n",i);

	return 0;
}