#include <fstream>
#include <cstdlib>
#include <ctime>
using namespace std;

ifstream fi("party.in");
ofstream fo("party.out");
int n,m;
int P[1001][2];
int X[101];

int cauta()
/// returneaza numarul de ordine al primei propozitii nesatisfacute
{
	for (int i=1;i<=m;i++)
	{
		/// valoarea de adevar a propozitiei i
		int a,b;
		if (P[i][0]>0)
			a=X[P[i][0]];
		else
			a=1-X[-P[i][0]];
		if (P[i][1]>0)
			b=X[P[i][1]];
		else
			b=1-X[-P[i][1]];
		if (a+b==0)
			return i;
	}
	return 0;
}

int main()
{
	srand(time(NULL));
	fi>>n>>m;
	for (int i=1;i<=m;i++)
	{
		int a,b,c;
		fi>>a>>b>>c;
		if (c==0)
		{
			P[i][0]=a;
			P[i][1]=b;
		}
		if (c==1)
		{
			P[i][0]=a;
			P[i][1]=-b;
		}
		if (c==2)
		{
			P[i][0]=-a;
			P[i][1]=b;
		}
		if (c==3)
		{
			P[i][0]=-a;
			P[i][1]=-b;
		}
	}
	/// se dau valori tuturor necunoscutelor
	for (int i=1;i<=n;i++)
		X[i]=1;
	/// cautari repetate ale unei propozitii care nu este satisfacuta
	while (1)
	{
		int poz=cauta();
		if (poz==0)
			break;
		else
		{
			int r;
			r=rand() % 2;
			int var;
			var=P[poz][r];
			if (var<0)
				var=-var;
			X[var]=1-X[var];
		}
	}
	int rez;
	rez=0;
	for (int i=1;i<=n;i++)
		rez=rez+X[i];
	fo<<rez<<"\n";
	for (int i=1;i<=n;i++)
		if (X[i]==1)
			fo<<i<<"\n";
	fi.close();
	fo.close();
	return 0;
}