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

struct rel {
	int a,b,z;
};

int n,m;
rel x[1000];
char v[101];

void citire() {
	FILE *fin = fopen("party.in", "rt");

	fscanf(fin, " %d %d", &n, &m);

	int i;

	for (i = 0; i < m; ++i)
		fscanf(fin, " %d %d %d", &x[i].a, &x[i].b, &x[i].z);

	fclose(fin);
}

int check() {
	int i;

	for (i = 0; i < m; ++i)
		switch(x[i].z) {
			case 0:
				if (v[x[i].a] == 0 && v[x[i].b] == 0) 
					return i;
				break;
			case 1:
				if (v[x[i].a] == 0 && v[x[i].b] == 1) 
					return i;
				break;
			case 2:
				if (v[x[i].a] == 1 && v[x[i].b] == 0) 
					return i;
				break;
			case 3:
				if (v[x[i].a] == 1 && v[x[i].b] == 1) 
					return i;
				break;
		}
	return -1;
}

void aleator() {
	int i, k=0, q=32677;

	for (i = 0; i <= n; ++i) 
		v[i]=0;

	while ((i = check()) != -1) {
		k = rand() & q;

		if (k < 16384) 
			v[x[i].a] = 1 - v[x[i].a];
		else
			v[x[i].b] = 1 - v[x[i].b];
	}

}

void afisare() {
	FILE *fout=fopen("party.out","wt");
	int i, nr = 0;

	for (i = 1;i <= n; ++i)
		if (v[i] == 1) ++nr;
	
	fprintf(fout, "%d\n", nr);

	for (i = 1; i <= n; ++i)
		if (v[i] == 1) 
			fprintf(fout, "%d\n", i);

	fclose(fout);
}

int main() {

	citire();
	
	aleator();

	afisare();

	return 0;
}