#include<bits/stdc++.h>
using namespace std;
ifstream F("party.in");
ofstream G("party.out");
int n,m,x[1001],y[1001],z[1001],i,t[202],c;
int main()
{
    for(srand(time(0)),F>>n>>m,i=1;i<=m;++i)
        F>>x[i]>>y[i]>>z[i];
    for(i=0;i-m-1;)
        for(i=1;i<=m;++i) {
            if((t[x[i]]<<1)|t[y[i]]-z[i])
                continue;
            if(rand()&1)
                t[x[i]]=1-t[x[i]];
            else
                t[y[i]]=1-t[y[i]];
            break;
        }
    for(i=1;i<=n;++i)
        c+=t[i];
    for(G<<c<<'\n',i=1;i<=n;++i)
        if(t[i]&1)
            G<<i<<'\n';
    return 0;
}