#include <fstream>
#include <cstdlib>
#include <ctime>

using namespace std;

struct COND{int x, y, type;};

bool satisfied(bool valX, bool valY, int type)
{
    switch(type)
    {
        case 0: return (valX || valY);
        case 1: return (valX || !valY);
        case 2: return (!valX || valY);
        case 3: return (!valX || !valY);
    }
    return true;
}

COND conditions[1001];
bool values[101];

int main()
{
    int n, m;
    int i;
    int nrGuests = 0;
    srand(time(NULL));
    ifstream f("party.in");
    f>>n>>m;
    for(i = 1; i <= m; i++)
        f>>conditions[i].x>>conditions[i].y>>conditions[i].type;
    f.close();
    for(i = 1; i <= n; i++)
        values[i] = true;
    for(i = 1; i <= m; i++)
    {
        if(!satisfied(values[conditions[i].x], values[conditions[i].y], conditions[i].type))
        {
            if(rand() % 2 == 0)
                values[conditions[i].x] = !values[conditions[i].x];
            else
                values[conditions[i].y] = !values[conditions[i].y];
            i = 0;
        }
    }
    for(i = 1; i <= n ; i++)
        if(values[i])
            nrGuests++;
    ofstream g("party.out");
    g<<nrGuests<<'\n';
    for(i = 1; i <= n; i++)
        if(values[i])
            g<<i<<'\n';
    g.close();
    return 0;
}