#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
using namespace std;

#define NMAX 105
#define pb push_back
#define sz size()

int N,M;
bool st[NMAX];
vector <int> edge[NMAX];

void read_data()
{
	short int u,v,type;
	scanf("%d %d",&N,&M);
	for(int i=0;i<M;i++)
	{
		scanf("%hd %hd %hd",&u,&v,&type);
		edge[u].pb((v<<2)|type);
		switch(type)
		{
			case 1:	type=2;
				break;
			case 2: type=1;
				break;
		}
		edge[v].pb((u<<2)|type);
	}
	for(int i=1;i<=N;i++)
		sort(edge[i].begin(),edge[i].end());
}

void back(int k)
{
	// solution
	if(k==N+1)
	{
		int cnt=0;
		for(int i=1;i<=N;i++)
			if(st[i])
				cnt++;
		printf("%d\n",cnt);
		for(int i=1;i<=N;i++)
			if(st[i])
				printf("%d\n",i);
		exit(0);
	}
	// verify
	short int state=-1,new_state;
	for(unsigned int i=0;(i<edge[k].sz)&&(edge[k][i]<(k<<2));i++)
	{
		new_state=-1;
		switch(edge[k][i]&3)
		{
			case 0:	if(!st[edge[k][i]>>2])
					new_state=1;
				break;
			case 1:	if(st[edge[k][i]>>2])
					new_state=1;
				break;
			case 2:	if(!st[edge[k][i]>>2])
					new_state=0;
				break;
			case 3:	if(st[edge[k][i]>>2])
					new_state=0;
				break;
		}
		if(state==-1)
			state=new_state;
		else
			if(state==0)
			{
				if(new_state==1)
					return;
			}
			else
			{
				if(new_state==0)
					return;
			}
	}
	// recursive call
	if(state==0)
	{
		st[k]=false;
		back(k+1);
		return;
	}
	else
		if(state==1)
		{
			st[k]=true;
			back(k+1);
			return;
		}
		else
		{
			st[k]=(bool)(rand()%2);
			back(k+1);
			st[k]=!st[k];
			back(k+1);
		}
}


int main()
{
	srand(N*10000+M);
	freopen("party.in","r",stdin);
	freopen("party.out","w",stdout);
	read_data();
	back(1);
	return 0;
}