#include<bits/stdc++.h>

#define all(s) s.begin(),s.end()
#define rc(x) return cout<<x<<endl,0
#define forn(i,n) for(int i=0;i<int(n);i++)

#define pb push_back
#define mp make_pair
#define fr first
#define sc second

typedef long long ll;
typedef long double ld;

const int nmax=103;
const int mod=998244353;
const ll inf=0x3f3f3f3f3f3f3f3f;

using namespace std;

int n,m,aux;
vector<int> v1(103,0),v2(103,0),v3(103,0);
bool ok,f[103];

bool verif()
{
  for(int i=1;i<=m;i++)
  {
    if(v3[i]==0)
    {
      if(!f[v1[i]] && !f[v2[i]]) return 0;
    } else
    if(v3[i]==1)
    {
      if(!f[v1[i]] && f[v2[i]]) return 0;
    } else
    if(v3[i]==2)
    {
      if(f[v1[i]] && !f[v2[i]]) return 0;
    } else
    if(v3[i]==3)
    {
      if(f[v1[i]] && f[v2[i]]) return 0;
    }
  }
  return 1;
}

void back(int k)
{
  if(!ok)
  {
    if(k>n)
    {
      if(verif() && aux!=0)
      {
        ok=true;
        cout<<aux<<"\n";
        for(int i=1;i<=n;i++) if(f[i]) cout<<i<<"\n";
      }
    } else
    {
      for(int i=0;i<2;i++)
      {
        if(i) aux++;
        f[k]=i;
        back(k+1);
        if(i) aux--;
      }
    }
  }
}

int main()
{
  freopen("party.in","r",stdin);
  freopen("party.out","w",stdout);
  ios_base::sync_with_stdio(0); cin.tie(0);
  cin>>n>>m;

  for(int i=1; i<=m; i++) cin>>v1[i]>>v2[i]>>v3[i];
  ok=false;
  back(1);
}