#include<fstream>
#include<stack>
#include<vector>
using namespace std;
int n, m, i, t, x, y, nr, cnt, num, j;
int viz[205], ff[205], f[205], ctc[205], low[205], niv[205], sol[205];
stack<int> s;
vector<int> v[205], w[205];
ifstream fin("party.in");
ofstream fout("party.out");
int inv(int x){
    if(x > n){
        return x - n;
    }
    return x + n;
}
void dfs(int nod){
    viz[nod] = f[nod] = 1;
    cnt++;
    low[nod] = niv[nod] = cnt;
    s.push(nod);
    for(int i = 0; i < v[nod].size(); i++){
        int vecin = v[nod][i];
        if(viz[vecin] == 0){
            dfs(vecin);
        }
        if(f[vecin] == 1){
            low[nod] = min(low[nod], low[vecin]);
        }
    }
    if(low[nod] == niv[nod]){
        nr++;
        int x;
        do{
            x = s.top();
            s.pop();
            ctc[x] = nr;
            f[x] = 0;
            w[nr].push_back(x);
        }while(x != nod);
    }
}
int main(){
    fin>> n >> m;
    for(i = 1; i <= m; i++){
        fin>> x >> y >> t;
        if(t == 1){
            y = inv(y);
        }
        else{
            if(t == 2){
                x = inv(x);
            }
            else{
                if(t == 3){
                    x = inv(x);
                    y = inv(y);
                }
            }
        }
        v[ inv(x) ].push_back(y);
        v[ inv(y) ].push_back(x);
    }
    for(i = 1; i <= n + n; i++){
        if(viz[i] == 0){
            dfs(i);
        }
    }
    for(i = 1; i <= nr; i++){
        if(ff[i] == 1){
            continue;
        }
        for(j = 0; j < w[i].size(); j++){
            x = w[i][j];
            sol[x] = 1;
            sol[ inv(x)] = 0;
            ff[ ctc[ inv(x) ] ] = 1;
        }
    }
    for(i = 1; i <= n; i++){
        num += sol[i];
    }
    fout<< num <<"\n";
    for(i = 1; i <= n; i++){
        if(sol[i] == 1){
            fout<< i <<"\n";
        }
    }
    return 0;
}