#include <cstdio>
#include <vector>
#include <bitset>
#include <stack>
#include <set>
using namespace std;

#define NMAX 210

typedef set<int>::iterator siter;
typedef vector<int>::iterator viter;

vector<int> g[NMAX];
set<int> cg[NMAX];
vector<vector<int> > cc;
int idx[NMAX],llink[NMAX],comp[NMAX],ts[NMAX],tidx=1,n,m,nc=0,tnc;
bitset<NMAX> viz,inStack,val;
stack<int> stk;

inline int non(int x){
	return (x>n)?x-n:x+n;	
}

void tarjan(int nod){
	idx[nod]=llink[nod]=tidx++;
	stk.push(nod),inStack[nod]=true;
	
	for(viter it=g[nod].begin();it!=g[nod].end();++it){
		if(!idx[*it]){
			tarjan(*it);
			llink[nod]=min(llink[*it],llink[nod]);	
		}else if(inStack[*it]){
			llink[nod]=min(llink[*it],llink[nod]);	
		}
	}
	
	if(llink[nod]==idx[nod]){
		vector<int> con;
		int nd;
		do{
			con.push_back(nd =  stk.top());
			stk.pop(),inStack[nd]=false;
			comp[nd]=nc;
		}while(nd!=nod);
		nc++;
		cc.push_back(con);
	}	
}

void build(){
	for(int i=0;i<nc;i++){
		for(int j=0;j<cc[i].size();j++){
			for(viter it=g[cc[i][j]].begin();it!=g[cc[i][j]].end();++it){
				cg[i].insert(comp[*it]);	
			}	
		}	
	}
}

void tsort(int nod){
	viz[nod]=true;
	for(siter it=cg[nod].begin();it!=cg[nod].end();++it){
		if(!viz[*it]){
			tsort(*it);
		}	
	}	
	ts[--tnc]=nod;
}

void solve(int nod){
	if(viz[nod]){
		for(viter it=cc[nod].begin();it!=cc[nod].end();it++){
			val[*it]=false;
			val[non(*it)]=true;
			viz[comp[non(*it)]]=false;	
		}
	}	
}

bool verif(){
	for(int i=1;i<=n;i++){
		if(comp[i]==comp[non(i)]){
			return false;	
		}	
	}	
	return true;
}

int main(){
	FILE* fin=fopen("party.in","r");
	FILE* fout=fopen("party.out","w");	
	
	fscanf(fin,"%d %d\n",&n,&m);
	
	for(int i=0,x,y,z;i<m;i++){
		fscanf(fin,"%d %d %d\n",&x,&y,&z);
		switch(z){
			case 0:
				g[x+n].push_back(y);
				g[y+n].push_back(x);
				break;
			case 1:
				g[x+n].push_back(y+n);
				g[y].push_back(x);
				break;
			case 2:
				g[y+n].push_back(x+n);
				g[x].push_back(y);
				break;
			case 3:
				g[x].push_back(y+n);
				g[y].push_back(x+n);
				break;
		}
	}
	
	for(int i=1;i<=n+n;i++){
		if(!idx[i]){
			tarjan(i);	
		}	
	}

	if(verif()){
		build();
				
		tnc=nc;
		for(int i=0;i<nc;i++){
			if(!viz[i]){
				tsort(i);	
			}	
		}
		
		for(int i=0;i<nc;i++){
			solve(ts[i]);	
		}
		
		vector<int> sol;
		for(int i=1;i<=n;i++){
			if(val[i]){
				sol.push_back(i);	
			}	
		}
		fprintf(fout,"%d\n",sol.size());
		for(viter it=sol.begin();it!=sol.end();++it){
			fprintf(fout,"%d\n",*it);	
		}
	}else{
		fprintf(fout,"0\n");
	}	
	fclose(fin);
	fclose(fout);
}