#include <fstream>
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <vector>
#include <cmath>
using namespace std;

ifstream fin("party.in");
ofstream fout("party.out");

vector<pair<int, int> >expr;
int n, m, p;
int sol[128];

void citire() {
    fin >> n >> m;
    for(int i = 1; i <= m; i++) {
        int x, y, z;
        fin >> x >> y>> z;
        if(z == 0)
            expr.push_back({x, y});
        else if (z == 1)
            expr.push_back({x, -y});
        else if (z == 2)
            expr.push_back({-x, y});
        else if (z == 3)
            expr.push_back({-x, -y});
    }
}

bool eval(pair<int, int> p) {
    int x = p.first;
    int y = p.second;

    return ( (x > 0 ? sol[abs(x)] : !sol[abs(x)]) | (y > 0 ? sol[abs(y)] : !sol[abs(y)]) );
}

void afis() {
    int nr = 0;
    for(int i = 1; i <= n; i++)
        if(sol[i])
            nr++;
    fout << nr << '\n';
    for(int i = 1; i <= n; i++)
        if(sol[i])
            fout << i << '\n';
}

void solve() {
    srand(time(0));
    for(int i = 1; i <= n; i++)
        sol[i] = rand()%2;

    while(true) {
        bool currRes = 1;
        for(int i = 0; i < expr.size(); i++) {
            currRes &= eval(expr[i]);
            if(!currRes) {
                p = i;
                break;
            }
        }

        if(currRes) {
            afis();
            return;
        }

        if(rand()%2)
            sol[abs(expr[p].first)] ^= 1;
        else
            sol[abs(expr[p].second)] ^= 1;
    }
}

int main() {
    citire();
    solve();
}