#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;

ifstream in("party.in");
ofstream out("party.out");

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

int main()
{
  //freopen("party.in","r",stdin);
  //freopen("party.out","w",stdout);
  ios_base::sync_with_stdio(0); cin.tie(0);
  in>>n>>m;
  for(int i=1; i<=m; i++) in>>v1[i]>>v2[i]>>v3[i];
  ok=false;
  while(!ok)
  {
    ok=true;
    for(int i=1;i<=m;i++)
    {
      if(v3[i]==0)
      {
        if(!f[v1[i]] && !f[v2[i]])
        {
          bool k=rand()%2;
          f[v1[i]]=k;
          f[v2[i]]=!k;
          ok=false;
        }
      } else
      if(v3[i]==1)
      {
        if(!f[v1[i]] && f[v2[i]])
        {
          f[v2[i]]=0;
          ok=false;
        }
      } else
      if(v3[i]==2)
      {
        if(f[v1[i]] && !f[v2[i]])
        {
          f[v1[i]]=0;
          ok=false;
        }
      } else
      if(v3[i]==3)
      {
        if(f[v1[i]] && f[v2[i]])
        {
          bool k=rand()%2;
          f[v1[i]]=k;
          f[v2[i]]=!k;
          ok=false;
        }
      }
    }
    if(!ok)
    {
      for(int i=1;i<=n;i++)
      if(f[i]) sol.pb(i);
    }
  }
  out<<sol.size();
  forn(i,sol.size()) out<<sol[i]<<"\n";
  return 0;
}