#include<stdio.h>
#include<stdlib.h>
#define Nm 101
#define Mm 1000
int X[Mm],Y[Mm],Z[Mm],V[Nm],A[Nm],n,m,k;

void read()
{
    int i;

    freopen("party.in","r",stdin);
    scanf("%d%d",&n,&m);
    for(i=0;i<m;++i)
        scanf("%d%d%d",X+i,Y+i,Z+i);
}

void solve()
{
    int i;

    srand(7);
    while(1)
    {
        for(i=0;i<m && V[X[i]]^((Z[i]&2)!=0)|V[Y[i]]^Z[i]&1;++i);
        if(i==m)
            break;
        if(rand()&1)
            V[X[i]]^=1;
        else
            V[Y[i]]^=1;
    }

    for(i=1;i<=n;++i)
        if(V[i])
            A[k++]=i;
}

void write()
{
    int i;

    freopen("party.out","w",stdout);
    printf("%d\n",k);
    for(i=0;i<k;++i)
        printf("%d\n",A[i]);
}

int main()
{
    read();
    solve();
    write();
    return 0;
}