#include <iostream>
#include <string>
#include <vector>
#include <sstream>
using namespace std;

class Set
{
  public:
    int size( ) const
    { return items.size( ); }

    bool isEmpty( ) const
    { return size( ) == 0; }

    void clear( )
    { items.clear( ); }

    bool add( const string & x )
    {
        if( contains( x ) )
            return false;
        items.push_back( x );
        return true;
    }

    bool remove( const string & x )
    {
        int pos = findPos( x );
        if( pos < 0 )
            return false;
        items[ pos ] = items.back( );
        items.pop_back( );
        return true;
    }

    bool contains( const string & x ) const
    {
        return findPos( x ) >= 0;
    }

  private:
    vector<string> items;

    int findPos( const string & x ) const
    {
        for( int i = 0; i < items.size( ); i++ )
            if( items[ i ] == x )
                return i;

        return -1;
    }
};


const int PRIME1 = 11;
const int PRIME2 = 13;
const int SIZE = 37;

string makeString( int x )
{
    ostringstream os;
    os << x;
    return os.str( );
}

int main( )
{
    Set s1;

    for( int i = PRIME1; i != 0; i =  (i + PRIME1 ) % SIZE )
    {
        s1.add( makeString( i ) );
    }

    cout << boolalpha;
    cout << "Size is: " << s1.size( ) << endl;

    for( int i = 1; i < SIZE; i++ )
        if( !s1.contains( makeString( i ) ) )
            cout << "OOPS #1 " << i << endl;

    if( s1.contains( makeString( SIZE ) )  )
        cout << "OOPS #2 " << s1.size( ) << endl;

    Set s2 = s1;
    Set s3;

    s3 = s1;

    for( int i = PRIME2; i != 0; i = ( i + PRIME2 ) % SIZE )
        s1.remove( makeString( i ) );

    for( int i = 0; i < SIZE; i++ )
        if( s1.contains( makeString( i ) ) )
            cout << "OOPS #3 " << i << endl;

    cout << "s1 Size is: " << s1.size( ) << endl;
    cout << "s2 Size is: " << s2.size( ) << endl;
    cout << "s3 Size is: " << s3.size( ) << endl;

    return 0;
}