#include <fstream>
#include <vector>
#define NMAX 2*108
using namespace std;
ifstream fin("party.in");
ofstream fout("party.out");
int n,m;
vector <int> g[NMAX];
vector <int> gt[NMAX];
vector <int> ans;
int ctc[NMAX],nrc;
bool uz[NMAX];
vector <int> postordine;
void dfs(int x);
void dfsg(int x);
int main()
{
    fin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        int x,y,c;
        fin>>x>>y>>c;
        ///a+n=A -a+n=!A
        if(c==0)
        {
            g[-x+n].push_back(y+n);
            gt[y+n].push_back(-x+n);
            g[-y+n].push_back(x+n);
            gt[x+n].push_back(-y+n);
        }
        else
        if(c==1)
        {
            g[-x+n].push_back(-y+n);
            gt[-y+n].push_back(-x+n);
            g[y+n].push_back(x+n);
            gt[x+n].push_back(y+n);
        }
        else
        if(c==2)
        {
            g[x+n].push_back(y+n);
            gt[y+n].push_back(x+n);
            g[-y+n].push_back(-x+n);
            gt[-x+n].push_back(-y+n);
        }
        else
        {
            g[x+n].push_back(-y+n);
            gt[-y+n].push_back(x+n);
            g[y+n].push_back(-x+n);
            gt[-x+n].push_back(y+n);
        }
    }
    for(int i=1;i<=n;i++)
    {
        if(!uz[-i+n])
            dfs(-i+n);
        if(!uz[i+n])
            dfs(i+n);
    }
    for(int i=postordine.size()-1;i>=0;i--)
    {
        if(uz[postordine[i]])
        {
            nrc++;
            dfsg(postordine[i]);
        }
    }
   // for(int i=1;i<=n;i++)
    //    fout<<ctc[-i+n]
    for(int i=1;i<=n;i++)
        if(ctc[i+n]>ctc[-i+n])
            ans.push_back(i);
    fout<<ans.size()<<'\n';
    for(int i=0;i<ans.size();i++)
        fout<<ans[i]<<'\n';
    return 0;
}
void dfs(int x)
{
    uz[x]=1;
    for(int i=0;i<g[x].size();i++)
    {
        if(!uz[g[x][i]])
        {
            uz[g[x][i]]=1;
            dfs(g[x][i]);
        }
    }
    postordine.push_back(x);
}
void dfsg(int x)
{
    uz[x]=0;
    ctc[x]=nrc;
    for(int i=0;i<gt[x].size();i++)
    {
        if(uz[gt[x][i]])
        {
            uz[gt[x][i]]=0;
            dfsg(gt[x][i]);
        }
    }
}