#include<iostream>
#include<vector>
#include<fstream>
using namespace std;

ifstream f("dfs.in");
ofstream g("dfs.out");

int n,m;
vector<int> graf[100100];
bool viz[100100];

void DFS(int nod)
{
    int i;
    viz[nod] = 1;
    cout<<nod<<" ";
    for(i=0;i<graf[nod].size();i++)
        if(viz[graf[nod][i]] == 0)
            DFS(graf[nod][i]);

}


int main()
{
    int i,x,y,nrc=0;
    f>>n>>m;
    for(i=1;i<=m;i++)
    {
        f>>x>>y;
        graf[x].push_back(y);
        graf[y].push_back(x);
    }

    for(i=1;i<=n;i++)
        if(!viz[i])
        {
            nrc++;
            DFS(i);
        }

    g<<nrc;
    return 0;












}