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

int viz[100000], componenta, n, m;
vector<int> adj[100000];
ifstream fin("dfs.in");
ofstream fout("dfs.out");

void dfs(int start) {
    cout<<start<<endl;
    for(vector<int>::iterator it = adj[start].begin(); it != adj[start].end(); ++it) {
        if(viz[*it] == 0) {
            viz[*it] = 1;
            dfs(*it);
        }
    }
}

int main() {
    int i, u, v;
    fin >> n >> m;
    for(i = 0; i < m; i++) {
        fin >> u >> v;
        u--, v--;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for(i = 0; i < n; i++) {
        if(viz[i] == 0) {
            viz[i] = 1;
            componenta++;
            dfs(i);
        }
    }
    fout << componenta;
    return 0;
}