#include <stdio.h>
#include <algorithm>
#include <stdlib.h>
#include <ctime>
#define Nmax 105
#define Mmax 1005
using namespace std;

struct op{ int tip,x,y; } a[Mmax];
int v[Nmax];
int i,n,m,ok,x,nr;

int main(){
	freopen("party.in","r",stdin);
   freopen("party.out","w",stdout);
   scanf("%d%d",&n,&m);
   for(i=1;i<=m;++i) scanf("%d%d%d",&a[i].x,&a[i].y,&a[i].tip);
   
   srand(time(NULL));
   for(i=1;i<=n;++i) v[i]=rand()%2;

   for(ok=1; ok; ){
   	ok=0;
   	for(i=1;i<=m;++i)
         if(a[i].tip == 0){
         	if(!v[a[i].x] && !v[a[i].y]){
            	ok=1;
            	x=rand()%2;
               if(x) v[a[i].x]=1; else v[a[i].y]=1;
            }
         } else
         if(a[i].tip == 1){
         	if(!v[a[i].x] && v[a[i].y]){
            	ok=1;
               v[a[i].y]=0;
            }
         }else
         if(a[i].tip == 2){
         	if(!v[a[i].y] && v[a[i].x]){
            	ok=1;
               v[a[i].x]=0;
            }
         } else
         if(a[i].tip == 3){
         	if( v[a[i].x] && v[a[i].y]){
            	x=rand()%2;
               if(x) v[a[i].x]=0; else v[a[i].y]=0;
               ok=1;
            }
         }
   }

   for(i=1;i<=n;++i) nr+=v[i];
   printf("%d\n",nr);
   for(i=1;i<=n;++i) if(v[i]) printf("%d\n",i);
   fclose(stdin); fclose(stdout);
   return 0;
}