#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
using namespace std;
#define BLACK 100
#define WHITE 200

#define FOR(i,n) for(int i=0;i<n;i++)

int **A;
int n;


class Graph{
    public:
        void assign(int **a);
        Graph() { count=0; }
        int Dfs(int st);
        int DfsVisit(int u,int color);
        void printBest();
        void setBest();
    private:
        int A[101][101];
        int N,count;
        int colour[101];
        bool isColoured[101];
        int best[101];
}g;    

void Graph::setBest()
{
    FOR(i,n) best[i]=colour[i];
}
void Graph::assign(int **a){
    N=n;
    count=0;
    FOR(i,n){
        colour[i]=0;
        isColoured[i]=-1;
        FOR(j,n) A[i][j]=a[i][j];
    }
}

void Graph::printBest()
{
    vector<int> best1;
    FOR(i,N) if(best[i]==BLACK) best1.push_back(i+1);
    int len=best1.size();
    FOR(i,len) {
        cout<<best1[i];
        if(i==len-1) cout<<"\n";
        else cout<<" ";
    }    
}    

int Graph::Dfs(int st){
    colour[st]=BLACK;
    DfsVisit(st,BLACK);
    count++;
    FOR(i,N){
        if(!colour[i]){
            bool flag=true;
            FOR(j,N){
                if(A[i][j]&&colour[j]==BLACK){ 
                    flag=false;
                    break;
                }
            }
            if(flag){
                colour[i]=BLACK;
                count++;
            }    
            else colour[i]=WHITE;
            DfsVisit(i,colour[i]);
        }
    }
    return count;
}

int Graph::DfsVisit(int u,int color){
    FOR(i,N){
        if(A[u][i]&&!colour[i]){
            bool flag=true;
            if(color==WHITE)
            FOR(j,N){
                if(A[i][j]&&colour[j]==BLACK){ 
                    flag=false;
                    break;
                }
            }
            if(color==WHITE&&flag){
                colour[i]=BLACK;
                count++;
            }    
            else colour[i]=WHITE;
            DfsVisit(i,colour[i]);
        }
    }
    return 0;
}  

int main()
{
    int k,x,y;
    int test;
    cin>>test;
    A=new int*[101];
    FOR(i,101) A[i]=new int[101];
    while(test--){
        cin>>n>>k;
        FOR(i,n) FOR(j,n) A[i][j]=0;
        FOR(i,k) {
            cin>>x>>y;
            A[x-1][y-1]=1;
            A[y-1][x-1]=1;
        }
        int mc=-1,c=0;
        FOR(i,n) {
            g.assign(A);
            c=g.Dfs(i);
            if(mc<c){
                mc=c;
                g.setBest();
            }    
        }
        cout<<mc<<endl;
        g.printBest();
    }    
    return 0;
}