#include <fstream>
#include <iostream>
#define MAX_N 105

using namespace std;

ifstream f("party.in");
ofstream g("party.out");
 
int n, m, sol;
bool val[MAX_N];
 
struct party
{
    int x, y, z;
    bool ok;
	
    void check ()
    {
        if (z == 0)
            ok = val[x] || val[y];
        if (z == 1)
            ok = val[x] || !val[y];
        if (z == 2)
            ok = !val[x] || val[y];
        if (z == 3)
            ok = !val[x] || !val[y];
    }
} v[1005];
 
bool valid()
{
    for (int i = 0; i < m; i ++)
    {
        v[i].check();
        if (!v[i].ok)
        {
            bool verif = rand() % 2;
            if (verif)
                val[v[i].x] = !val[v[i].x];
            else
                val[v[i].y] = !val[v[i].y];
            return false;
        }
    }
    return true;
}
 
int main()
{
    f >> n >> m;
    for (int i = 0; i < m; i ++)
        f >> v[i].x >> v[i].y >> v[i].z;
	
    for (int i = 1; i <= n; i ++)
        val[i] = rand() % 2;
	
    while (!valid());
		for (int i = 1; i <= n; i ++)
			sol += val[i];
		
    g << sol << "\n";
    for (int i = 1; i <= n; i ++)
        if (val[i])
            g << i << "\n";
 
    f.close();
    g.close();
    return 0;
 
}