#include <fstream>
#include <bitset>
using namespace std;
typedef struct rel{
        int tip,x,y;
        };
int N,M,nr;
bitset<101> inv,viz;
bitset<101> binv,bviz;
bitset<1001> u,bu;
rel v[1001];
bool ok;
ifstream f("party.in");
ofstream g("party.out");
void redu(int i,int val){
     int j;
     if (viz[i] && inv[i]!=val) ok=false;
     viz[i]=1;inv[i]=val;
     if (val==1){
     for (j=1;j<=M;++j)
       if (!u[j])
        if (v[j].x==i || v[j].y==i)
         switch(v[j].tip){
         case 0:u[j]=1;
                break;
         case 1:u[j]=1;
                if (v[j].y==i) redu(v[j].x,1);
                break; 
         case 2:u[j]=1;
                if (v[j].x==i) redu(v[j].y,1);
                break;
         case 3:u[j]=1;
                if (v[j].x==i) redu(v[j].y,0);
                  else redu(v[j].x,0);
                break;
                }
          }else{
     for (j=1;j<=M;++j)
       if (!u[j])
        if (v[j].x==i || v[j].y==i)
         switch(v[j].tip){
         case 0:u[j]=1;
                if (v[j].x==i) redu(v[j].y,1);
                  else redu(v[j].x,1);
                break;
         case 1:u[j]=1;
                if (v[j].x==i) redu(v[j].y,0);
                break;
         case 2:u[j]=1;
                if (v[j].y==i) redu(v[j].x,0);
                break;
         case 3:u[j]=1;
              }
              }
                        
          
         }
void backup(){
     int i;
     ok=true;
     for ( i=1;i<=N;++i)
      bviz[i]=viz[i],binv[i]=inv[i];
     for (i=1;i<=M;++i)
      bu[i]=u[i];
     }
void restore(){
     int i;
     for (i=1;i<=N;++i)
      viz[i]=bviz[i],inv[i]=binv[i];
     for (i=1;i<=M;++i)
      u[i]=bu[i];
     }
int main(){
    int i;
    f>>N>>M;
    for (i=1;i<=M;++i)
      f>>v[i].x>>v[i].y>>v[i].tip;
    for (i=1;i<=M;++i)
      if (v[i].x==v[i].y){
         u[i]=1;
         if (v[i].tip==0) redu(v[i].x,1);
         if (v[i].tip==3) redu(v[i].x,0);}         
    for (i=1;i<=N;++i)
      if (!viz[i]){
      backup();
      redu(i,1);
      if (!ok) restore(),redu(i,0);
      }
    for (i=1;i<=N;++i)
     if (inv[i]==1) ++nr;
    g<<nr<<'\n';;
    for (i=1;i<=N;++i)
     if (inv[i]==1) g<<i<<'\n';  
    return 0;
}