/*
	================== DEPTH FIRST SEARCH ==================
*/
#include <bits/stdc++.h>
using namespace std;
 
void DFS ( int node, vector<int>* G, vector<bool>& visited ){
 
	// print the visited node
	cout << node << " ";
	// mark the current node as visited
	visited[node] = true;
 
	// for all the adjacent nodes of the current node
	for( int adj : G[node] ){
		// if the adjacent node is not already visited then visit it
		if( !visited[adj] )
		  DFS( adj, G, visited );
	} 
} 
 
int main() {
 
	// V = number of vertices, E = number of edges
    int V, E;
    cin >> V >> E;
 
    // adjacency list 
    vector<int>* G = new vector<int>[V];
    vector<bool> visited(V, false);
 
    int p,q;
    while(E--){
        cin>>p>>q;
        // As it is an undirected graph we are pushing two edges between one pair of vertices
        G[p].push_back(q);	
        G[q].push_back(p);
    }
 
    // Visiting all the Verices once in Depth First Manner
    for( int i=0 ; i<V ; i++ ){
    	if( !visited[i] )
    		DFS(i, G, visited);
    }
 
  return 0;
}

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