#include <fstream>
#include <vector>
using namespace std;
int n, m, nrsol;
vector <int> G[210], GT[210];
bool viz[210], sol[210];
int postordine[210], nrord;

inline int Not(int x)
{
	if(x <= n)
		return x + n;
	return x - n;
}

inline void Citire()
{
	int i, x, y, tip;
	ifstream fin("party.in");
	fin >> n >> m;
	for(i = 1; i <= m; ++i)
	{
		fin >> x >> y >> tip;
		if(tip == 0); // x sau y
		else
		{
			if(tip == 1) // x sau !y
				y = Not(y);
			else
			{
				if(tip == 2) // !x sau y
					x = Not(x);
				else // !x sau !y
				{
					x = Not(x);
					y = Not(y);
				}
			}
		}
		G[Not(x)].push_back(y);
		G[Not(y)].push_back(x);
		GT[x].push_back(Not(y));
		GT[y].push_back(Not(x));
	}
	fin.close();
}

inline void DFS(int x)
{
	viz[x] = true;
	vector <int>::iterator it;
	for(it = G[x].begin(); it != G[x].end(); ++it)
		if(!viz[*it])
			DFS(*it);
	postordine[++nrord] = x;
}

inline void DFST(int x)
{
	viz[x] = false;
	sol[Not(x)] = true;
	vector <int>::iterator it;
	for(it = GT[x].begin(); it != GT[x].end(); ++it)
		if(viz[*it])
			DFST(*it);
}

inline void Rezolvare()
{
	int i;
	for(i = 1; i <= 2 * n; ++i)
		if(!viz[i])
			DFS(i);
	for(i = 2 * n; i > 0; --i)
		if(viz[postordine[i]] && viz[Not(postordine[i])])
			DFST(postordine[i]);
	for(i = 1; i <= n; ++i)
		if(sol[i])
			nrsol++;
}

inline void Afisare()
{
	ofstream fout("party.out");
	fout << nrsol << "\n";
	for(int i = 1; i <= n; ++i)
		if(sol[i])
			fout << i << "\n";
	fout.close();
}

int main()
{
	Citire();
	Rezolvare();
	Afisare();
	return 0;
}