#include <fstream>
#include <vector>
#define NMax 110
#define MMax 1010

using namespace std;

bool existaSol;
int n, m;
bool sol[2*NMax];
bool viz[2*NMax];
vector <int> G[2*NMax], GT[2*NMax], ans;
int postordine[2*NMax], npostordine;

inline int neg(const int &x)
{
    if (x <= n)
        return x + n;
    return x - n;
}

void Read()
{
    ifstream f ("party.in");
    f>>n>>m;
    for (int i = 1; i<=m; ++i)
    {
        int x, y, cod;
        f>>x>>y>>cod;
        switch(cod)
        {
            case 0:
                // x||y
                break;
            case 1:
                // x || !y
                y = neg(y);
                break;
            case 2:
                // !x || y
                x = neg(x);
                break;
            case 3:
                // !x || !y
                x = neg(x);
                y = neg(y);
                break;
        }
        G[neg(x)].push_back(y);
        G[neg(y)].push_back(x);
        GT[y].push_back(neg(x));
        GT[x].push_back(neg(y));
    }
    f.close();
}

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

inline void DFST(const int node)
{
    if (sol[node])
    {
        existaSol = false;
        return ;
    }
    sol[neg(node)] = true;
    viz[node] = false;
    for (vector <int>::iterator it = GT[node].begin(); it!=GT[node].end(); ++it)
        if (viz[*it])
            DFST(*it);
}

void Solve()
{
    existaSol = true;
    int i, n2;
    n2 = n + n;
    for (i=1; i<=n2; ++i)
        if (!viz[i])
            DFS(i);
    for (i=n2; i; --i)
        if (viz[postordine[i]] && viz[postordine[neg(i)]])
            DFST(postordine[i]);
    for (i=1; i<=n; ++i)
        if (sol[i])
            ans.push_back(i);
}

void Write()
{
    ofstream g("party.out");
    g<<ans.size()<<"\n";
    for (vector <int>::iterator it = ans.begin(); it != ans.end(); ++it)
        g<<*it<<"\n";
    g.close();
}

int main()
{
    Read();
    Solve();
    Write();
    return 0;
}