#include <iostream>
#include <vector>
 
template<typename T, typename Allocator = std::allocator<T>>
class Vector: public std::vector<T, Allocator>
{
   using basic = std::vector<T, Allocator>;
public:
   using basic::basic;
   using basic::operator =;
 
   template <typename U, typename OtherAllocator = std::allocator<U>>
   Vector & operator =(const Vector<U, OtherAllocator>& other) {
      this->assign(other.begin(), other.end());
      return *this;
   }
};
 
int main()
{
   Vector<int> vi{1,2,3,4,5};
   Vector<double> vd;
   vd = vi;
   for (double d : vd)
      std::cout << d << " ";
}

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