#include<fstream>
using namespace std;
struct cerinta {
    int x,y,z;
} str[1001];
bool v[101];
inline bool check(int i)
{
    if(str[i].z==0)
        return v[str[i].x] || v[str[i].y];
    if(str[i].z==1)
        return v[str[i].x] || !v[str[i].y];
    if(str[i].z==2)
        return v[str[i].y] || !v[str[i].x];
    if(str[i].z==3)
        return v[str[i].x]+v[str[i].y]!=2;
    return false;
}
int main()
{
    int n,m,i;
    ifstream q("party.in");
    ofstream w("party.out");
    q>>n>>m;
    for(i=1; i<=m; i++)
        q>>str[i].x>>str[i].y>>str[i].z;
    for(i=1; i<=n; i++)
        v[i]=true;
    for(i=1; i<=m; i++)
        if(!check(i))
        {
            v[str[i].y]=!v[str[i].y];
            i=0;
        }
    m = 0;
    for(i=1; i<=n; i++)
        if(v[i])
            m++;
    w<<m<<"\n";
    for(i=1; i<=n; i++)
        if(v[i])
            w<<i<<"\n";
    return 0;
}