#include<fstream>
using namespace std;
typedef struct celula {
           int nod;
           celula *next;
           }*lista;
lista graf[205],v,tgraf[205];
int x,y,op,n,m,i,stiva[205],st,comp[205],nrc,assign[205];
bool viz[205];

int negat(int x) {
   if (x>n) return x-n;
    else return x+n;
}

void dfs(int nod) {
  viz[nod]=1;
  for (lista p=graf[nod]; p; p=p->next)
   if (viz[p->nod]==0) dfs(p->nod);
   
  ++st; stiva[st]=nod;    
     
}

void dfs2(int nod) {
  comp[nod]=nrc;
  assign[negat(nod)]=1;
  for (lista p=tgraf[nod]; p; p=p->next)
   if (comp[p->nod]==0) dfs2(p->nod);
}

int main(void) {
    ifstream fin("party.in");
    ofstream fout("party.out");
    
    fin>>n>>m;
    
    for (i=1; i<=m; ++i){
        fin>>x>>y>>op;
        if (op==1) y=negat(y);
        else if (op==2) x=negat(x);
        else if (op==3) { x=negat(x); y=negat(y); }
        
        int xn=negat(x), yn=negat(y);
        
        v=new celula; v->nod=y; v->next=graf[xn]; graf[xn]=v;
        v=new celula; v->nod=x; v->next=graf[yn]; graf[yn]=v;
        
        v=new celula; v->nod=xn; v->next=tgraf[y]; tgraf[y]=v;
        v=new celula; v->nod=yn; v->next=tgraf[x]; tgraf[x]=v;
        }   
    
       
    for (i=1; i<=2*n; ++i)
     if (viz[i]==0) dfs(i);
    
    for (i=st; i>=1; --i) 
     if ( comp[stiva[i]]==0 && comp[negat(stiva[i])]==0 ) { ++nrc; dfs2(stiva[i]); }
     
     int sol=0;
     for (i=1; i<=n; ++i) sol+=assign[i];
     fout<<sol<<"\n";
     for (i=1; i<=n; ++i)
     if (assign[i]==1) fout<<i<<"\n";
         
    
    return 0;
}