#include <bits/stdc++.h>

using namespace std;

#define FILE_IO

int N, M;
vector <int> edg[205], redg[205];
int O, ord[205];
int f[205];
int C, cmp[205];
vector <int> scc[205];
vector <int> sccedg[205];
int g[205];
int ans[205], v[205];
vector <int> party;

inline int node(int x) { return x > 0 ? x : -x + N; }
inline int value(int x) { return x <= N ? x : -x + N; }

void DFS1(int nod)
{
    if(f[nod])  return;
    f[nod] = 1;
    for(auto nxt: edg[nod])
        DFS1(nxt);
    ord[++O] = nod;
}

void DFS2(int nod)
{
    if(f[nod] == 2) return;
    f[nod] = 2;
    cmp[nod] = C;
    scc[C].push_back(nod);
    for(auto nxt: redg[nod])
        DFS2(nxt);
}

void solveDFS(int nod, int fth)
{
    if(ans[nod] == -1)
    {
        ans[nod] = fth;
        for(auto x: scc[nod])
        {
            int rev = node( -value(x) );
            ans[ cmp[rev] ] = 1 ^ fth;
        }
    }
    assert(!fth || (fth == ans[nod]));

    for(auto nxt: sccedg[nod])
    {
        g[nxt]--;
        if(g[nxt] == 0)
            solveDFS(nxt, fth | ans[nod]);
    }
}

int main()
{
    #ifdef FILE_IO
    freopen("party.in", "r", stdin);
    freopen("party.out", "w", stdout);
    #endif

    scanf("%d%d", &N, &M);
    for(int i = 1; i <= M; i++)
    {
        int x, y, op;
        scanf("%d%d%d", &x, &y, &op);
        if(op == 0)
        {
            edg[node(-x)].push_back(y);
            edg[node(-y)].push_back(x);
        }
        else if(op == 1)
        {
            edg[node(-x)].push_back(node(-y));
            edg[node(y)].push_back(node(x));
        }
        else if(op == 2)
        {
            edg[node(x)].push_back(node(y));
            edg[node(-y)].push_back(node(-x));
        }
        else if(op == 3)
        {
            edg[node(x)].push_back(node(-y));
            edg[node(y)].push_back(node(-x));
        }
    }

    for(int i = 1; i <= 2 * N; i++) DFS1(i);
    for(int i = 1; i <= 2 * N; i++)
        for(auto x: edg[i])
            redg[x].push_back(i);
    reverse(ord + 1, ord + 2 * N + 1);
    for(int i = 1; i <= 2 * N; i++)
        if( f[ ord[i] ] != 2 ) ++C, DFS2(ord[i]);

    for(int i = 1; i <= N; i++) assert(cmp[i] != cmp[i + N]);

    for(int i = 1; i <= C; i++) f[i] = 0;
    for(int i = 1; i <= C; i++)
        for(auto nod: scc[i])
            for(auto nxt: edg[nod])
                if(i != cmp[nxt])
                    if(f[ cmp[nxt] ] != i)
                        sccedg[i].push_back(cmp[nxt]), g[ cmp[nxt] ]++, f[ cmp[nxt] ] = i;

    for(int i = 1; i <= C; i++) ans[i] = -1;
    for(int i = 1; i <= C; i++)
        if(ans[i] == -1)    solveDFS(i, 0);

    for(int i = 1; i <= C; i++)
        for(auto nod: scc[i])
            v[nod] = ans[i];

    for(int i = 1; i <= N; i++)
        if(v[i])
            party.push_back(i);

    printf("%d\n", party.size());
    for(auto x: party)
        printf("%d\n", x);

    return 0;
}