//Ciucuialaaaaa!

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

bool sol[115];

struct relation
{
	int x, y, type;
} x[1024];

bool bad(relation A)
{
	if (A.type == 0 && sol[A.x] == 0 && sol[A.y] == 0)
		return true;
	if (A.type == 1 && sol[A.x] == 0 && sol[A.y] == 1)
		return true;
	if (A.type == 2 && sol[A.x] == 1 && sol[A.y] == 0)
		return true;
	if (A.type == 3 && sol[A.x] == 1 && sol[A.y] == 1)
		return true;
	return false;
}

int main()
{
	int i, N, M, cnt = 0;
	
	freopen("party.in", "r", stdin);
	freopen("party.out", "w", stdout);
	
	srand(time(0));

	scanf("%d%d", &N, &M);
	for (i = 1; i <= M; i ++)
		scanf("%d%d%d", &x[i].x, &x[i].y, &x[i].type);
	
	bool isSolution;
	
	do
	{
		isSolution = true;
		for (i = 1; i <= M; i ++)
			if (bad(x[i]))
			{
				int X = x[i].x, Y = x[i].y;
				int which = rand() % 2;
				if (which == 0)
				{
					cnt = cnt - sol[X];
					sol[X] = 1 - sol[X];
					cnt = cnt + sol[X];
				}
				else
				{
					cnt = cnt - sol[Y];
					sol[Y] = 1 - sol[Y];
					cnt = cnt + sol[Y];
				}
				isSolution = false;
				break;
			}
			
		if (cnt == 0 && isSolution == true)
		{
			sol[rand() % N + 1] = 1; cnt ++;
			isSolution = false;
		}
	}
	while (isSolution == false);
	
	printf("%d\n", cnt);
	for (i = 1; i <= N; i ++)
		if (sol[i])
			printf("%d\n", i);
	
	return 0;
}