ArrayList Generic

interface Arrayable<T> 
{
  void push_back(T x); // insert element to the end of array
  T pop_back();	       // return and remove the last element
  T min();             // return minimum in array
  T max();             // return maximum in array
  T sum();             // return sum of elements in array. Implement for Integer, Long, Double
  boolean Empty();     // check if array is empty
  int size();          // return size of array
}

class MyArray<T extends Number & Comparable<T>> implements Arrayable<T> 
{
  ArrayList<T> m;
  ...
}