#include<bits/stdc++.h>

#define NMAX 202
#define ll long long

using namespace std;

int n, m, a, b, c, F = 101, T = 102, viz[NMAX], uz[NMAX];
vector<int> v[2 * NMAX], v2[2 * NMAX], H, ans;
void dfs(int nod){
    uz[nod] = 1;
    for (auto it : v[nod]) if (!uz[it]) dfs(it);
    H.push_back(nod);
}
void dfs2(int nod){
    //assert(!viz[nod]);
    uz[nod] = 0; viz[nod ^ 1] = 1;
    if (nod&1) ans.push_back(nod/2 + 1);
    for (auto it : v2[nod]) if (uz[it]) dfs2(it);
}
void add(int a, int b){
    a = (a < 0 ? -a * 2 - 1 : a * 2 - 2);
    b = (b < 0 ? -b * 2 - 1 : b * 2 - 2);
    v[a^1].push_back(b);
    v[b^1].push_back(a);
    v2[a].push_back(b^1);
    v2[b].push_back(a^1);
}
int main(){
    freopen("party.in","r",stdin);
    freopen("party.out","w",stdout);
    cin >> n >> m;
    for (int i=1;i<=m;i++){
        cin >> a >> b >> c;
        if (c == 0){
            add(a, b);
        }
        else if (c == 1){
            add(a, -b);
        }
        else if (c == 2){
            add(-a, b);
        }
        else{
            add(-a, -b);
        }
    }
    for (int i=0;i<2*n;i++) if (!uz[i]) dfs(i);
    reverse(H.begin(), H.end());
    for (auto it : H){
        if (uz[it] && uz[it^1]) dfs2(it);
    }

    cout << ans.size() << '\n';
    for (auto it : ans)
        cout << it << '\n';



    return 0;
}