#include<stdio.h>
int n,m,i,j,k,a,b,cod,ad[201][201],nr,t[201],mt,cont,step;
int cauta();
int main()
{
	FILE *f,*g;
	f=fopen("party.in","r");
	g=fopen("party.out","w");
	fscanf(f,"%d%d",&n,&m);
	for(i=1;i<=m;i++)
	{ fscanf(f,"%d%d%d",&a,&b,&cod);
	  if(cod==0){ ad[a+n][b]=1;ad[b+n][a]=1;}
	  if(cod==1){ ad[a+n][b+n]=1;ad[b][a]=1;}
	  if(cod==2){ ad[a][b]=1;ad[b+n][a+n]=1;}
	  if(cod==3){ ad[a][b+n]=1;ad[b][a+n]=1;}
	}
	for(i=1;i<=2*n;i++)
	{ cont=1;step=1;
	  while(cont)
	   {  cont=0;
	      for(j=1;j<=2*n;j++)
	       if(ad[i][j]==step)
		for(k=1;k<=2*n;k++)
		 if(ad[j][k])
		  if(!ad[i][k])
		   {ad[i][k]=step+1;cont++;}
	    step++;
	   }
	}
	mt=0;
	while(mt<n)
	{  for(i=1;i<=n;i++)
	    if(!t[i])
	     if(!ad[i][n+i])
	      {  t[i]=1;t[n+i]=-1;mt++;
		 for(j=1;j<=n;j++)
		  if(ad[i][j]&&!t[j])
		   {t[j]=1;t[j+n]=-1;mt++;}
		 for(j=n+1;j<=2*n;j++)
		  if(ad[i][j]&&!t[j])
		   {t[j]=1;t[j-n]=-1;mt++;}
		 break;
	      }
        }
	nr=n;
	for(i=1;i<=n;i++)
	nr+=t[i];
	nr/=2;
	fprintf(g,"%d\n",nr);
	for(i=1;i<=n;i++)
	 if(t[i]==1)
	  fprintf(g,"%d\n",i);
	fcloseall();
	return 0;
}