#include <iostream>
#include <set>
#include <vector>

using namespace std ;

int main()
{
	vector<int> v1 ;
	set<int> set1 ;

	v1.push_back( 4 ) ; v1.push_back( 2 ) ; v1.push_back( 4 ) ;
	v1.push_back( 1 ) ; v1.push_back( 2 ) ;
	for( int x1 : v1 )
	 cout << x1 << " " ;
	cout << endl ;

    int left = 0 ;
    //set1.insert(  v1[0] ) ;
	for( int x1 : v1 )
	  {
		//not seen before
        if ( set1.count( x1 ) == 0 )
           {
              v1[left++] = x1 ;
		   }
        else
           {

		   }
		  set1.insert( x1 ) ;
	  } //for

      v1.resize( left ) ;



	for( int x1 : v1 )
	 cout << x1 << " " ;
	cout << endl ;


	return 0;
}