#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#define dim 101
#define dim2 dim*10

int n, m, a[dim2][3], v[dim];

int main() {
	int i, ok, ct, op;
	freopen("party.in", "r", stdin);
	freopen("party.out", "w", stdout);
	
	scanf("%d %d\n", &n, &m);
	for (i=1; i<=m; ++i) scanf("%d %d %d\n", &a[i][0], &a[i][1], &a[i][2]);
	
	srand((unsigned)time(NULL));
	for (i=1; i<=n; ++i) v[i]=rand()%2;
	
	ok=0;
	while (!ok) {
		ok=1;
		for (i=1; i<=m && ok; ++i)
			if (a[i][2]==0) {
				if (!v[a[i][0]] && !v[a[i][1]]) {
					op=rand()%2;
					v[a[i][op]]=1;
					ok=0;
				}
			}
			else if (a[i][2]==1) {
				if (!v[a[i][0]] && v[a[i][1]]) {
					op=rand()%2;
					if (!op) v[a[i][0]]=1;
					else v[a[i][1]]=0;
					ok=0;
				}
			}
			else if (a[i][2]==2) {
				if (v[a[i][0]] && !v[a[i][1]]) {
					op=rand()%2;
					if (!op) v[a[i][0]]=0;
					else v[a[i][1]]=1;
					ok=0;
				}
			}
			else {
				if (v[a[i][0]] && v[a[i][1]]) {
					op=rand()%2;
					v[a[i][op]]=0;
					ok=0;
				}
			}
	}
	
	ct=0;
	for (i=1; i<=n; ++i)
		if (v[i]) ct++;
	
	printf("%d\n", ct);
	for (i=1; i<=n; ++i)
		if (v[i]) printf("%d\n", i);
	
	return 0;
}