#include <fstream>
#include <vector>
#include <queue>

#define MAX 262144
#define pb push_back

using namespace std;

vector<int> Go[MAX], Gi[MAX], discovered, part;
vector< vector < int > > v;
int where[MAX], value[MAX], n, m, a, b, c, first, second;
bool used[MAX];

inline int abs(int a)
{
    if(a > 0) return a;
    return -a;
}

inline int getNr(int a)
{
    if(a > 0) return a;
    else return abs(a) + n;
}

inline int getOpposite(int a)
{
    if(a <= n) return a + n;
    else return a - n;
}

void Citire()
{
    ifstream in("party.in");
    in>>n>>m;
    for(int i = 1; i <= m; i++)
    {
        in>>a>>b>>c;
        switch(c)
        {
            case 0: first = getOpposite(a); second = getOpposite(b); break;
            case 1: first = getOpposite(a); second = b; break;
            case 2: first = a; second = getOpposite(b); break;
            case 3: first = a; second = b; break;
        }
        Go[first].pb(b);
        Go[second].pb(a);
        Gi[a].pb(second);
        Gi[b].pb(first);
    }
    in.close();
}

void DFF(int nod)
{
    used[nod] = true;
    for(int i = 0; i < Go[nod].size(); i++)
        if(!used[Go[nod][i]])
            DFF(Go[nod][i]);
    discovered.pb(nod);
}

void DFS(int nod, int value)
{
    where[nod] = value;
    part.pb(nod);
    for(int i = 0; i < Gi[nod].size(); i++)
        if(!where[Gi[nod][i]])
            DFS(Gi[nod][i], value);
}

void Kosaraju()
{
    for(int i = 1; i <= 2 * n; i++)
        if(!used[i]) DFF(i);
    int contor = 1;
    for(; discovered.size(); discovered.pop_back())
        if(!where[discovered.back()])
        {
            part.clear();
            DFS(discovered.back(), contor++);
            v.pb(part);
        }
}

void Assign()
{
    for(int i = 0; i < v.size(); i++)
    {
        if(!value[i + 1])
            value[i + 1] = 2;
        for(int j = 0; j < v[i].size(); j++)
        {
            int nod = v[i][j];
            if(!value[where[getOpposite(nod)]])
                value[where[getOpposite(nod)]] = 3 - value[i + 1];
        }
    }
}

void Afisare()
{
    ofstream out("party.out");
    int contor = 0;
    for(int i = 1; i <= n; i++)
        if(value[where[i]] == 1) contor++;
    out<<contor<<"\n";
    for(int i = 1; i <= n; i++)
        if(value[where[i]] == 1)
            out<<i<<"\n";
    out.close();
}

int main()
{
    Citire();
    Kosaraju();
    Assign();
    Afisare();
    return 0;
}