#include<fstream>
#include<cstdlib>
using namespace std;
ifstream fi("party.in");
ofstream fo("party.out");
const int maxz = 1005;
const int maxn = 105;
bool este[maxn];
int i,n,m,x,y,z;
int nr=0;
struct triplet{
       int x,y,z;
       bool verific(){
                      if(z==0) return(este[x] || este[y]);
                      if(z==1) return(este[x] || !este[y]);
                      if(z==2) return(!este[x] || este[y]);
                      if(z==3) return(!(este[x] && este[y]));
                      return 1;
                     }
       void select_random(){
                            int r=rand()%2;
                            if(r==0) este[x]=!este[x];
                            else este[y]=!este[y];
                           }
};
triplet t[maxz];
int main(){
    fi>>n>>m;
    for(i=1;i<=m;i++) fi>>t[i].x>>t[i].y>>t[i].z;
    for(i=1;i<=n;i++) este[i]=1;
    i=1;
    while(i<=m){
                if(!t[i].verific()){ t[i].select_random(); i=1; }
                else i++;
               }
    for(i=1;i<=n;i++) if(este[i]) nr++;
    fo<<nr<<"\n";
    for(i=1;i<=n;i++) if(este[i]) fo<<i<<"\n";
    fi.close();
    fo.close();
    return 0;
}