struct Data {
    Data( int s ) :
        _data( new int[ s ] ),
        _size( s )
    {}
    Data( const Data &other ) :
        _data( new int[ other._size ] ),
        _size( other._size )
    {
        std::copy( other._data, other._data + _size, _data );
    }
    ~Data() {
        delete[] _data;
    }
    Data &operator=( const Data &other ) {
        if ( this == &other )
            return *this;
        
        delete[] _data;
        _size = other._size;
        _data = new int[ _size ];
        std::copy( other._data, other._data + _size, _data );
        
        return *this;
    }
    size_t size() const {
        return _size;
    }
    int &operator[]( size_t i ) {
        return _data[ i ];
    }
    int operator[]( size_t i ) const {
        return _data[ i ];
    }
private:
    int *_data;
    size_t _size;
};