#include<stdio.h>
#include<stdlib.h>
#include<time.h>

struct expresie{int a,b,ok;}v[1005];
int n,m,i,j,A,nr;
bool a[103],ready;

bool eval(expresie x){
if(x.ok == 0)
	return a[x.a]||a[x.b];
else
	if(x.ok == 1){
		if(!a[x.a])
			return (!a[x.b]);
		else
			return true;
		}
else
	if(x.ok == 2){
		if(!a[x.b])
			return (!a[x.a]);
		else
			return true;
	}
else
	return (!(a[x.a] && a[x.b]));
	
}

int main(){
freopen("party.in","r",stdin);
freopen("party.out","w",stdout);

scanf("%d %d",&n,&m);
srand(time(0));
for(i = 1 ; i <= m ; i++)
	scanf("%d %d %d",&v[i].a,&v[i].b,&v[i].ok);

for(i = 1; i <= n ; i++)
	a[i] = rand()%2;
while(!ready){
ready = true;

for(i = 1; i <= m ; i++)
	if(!eval(v[i])){
		A = rand()%2+1;
		if(A == 1)
			a[v[i].a] = !a[v[i].a];
		else
			a[v[i].b] = !a[v[i].b];
		ready = false;
		}
}

for(i = 1 ; i <= n ;i++)
	if(a[i])nr++;

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