dfs_recursion

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class graph {

    int n,e;
    HashMap<Integer,ArrayList<Integer>> list = new HashMap();
    boolean v[];
    
    
    //Constructor takes input
    graph(){
       
       n = i();      //no of nodes 
       e = i();      //no of egdes
       
       for(int i=0;i<e;i++)               //creating adjacency list
       {
            int a = i();
            int b = i();
           
            if(!list.containsKey(a))
                list.put(a,new ArrayList());
           
            if(!list.containsKey(b))
                list.put(b,new ArrayList());
           
           list.get(a).add(b);
           list.get(b).add(a);
       }
       
       v = new boolean[n+1];
      
    }
    
    public void dfs(int root)
    {
        v[root] = true;
        ArrayList<Integer> ar = list.get(root);
        
        for(int i=0;i<ar.size();i++)
        {
            int node = ar.get(i);
            if(!v[node])      // if element is not visited
            {
                dfs(node);
            }
        }
    }
    
    void p()
    {    
        System.out.print();
    }    
    
    public static void main(String[] args) {
        
       graph g = new graph();
       int root = 1;
       g.dfs(root);
    }
    
    
   static Scanner sc = new Scanner(System.in);
  
   static long l(){
        return sc.nextLong();
    }
    static int i(){
        return sc.nextInt();
    }
    static String s(){
        return sc.nextLine();
}
}