#include <vector>
#include <iostream>
 
template <typename T>
void foo(T begin, T end)
{
  for (; begin != end; ++begin)
  {
    std::cout << " " << *begin;
  }
}
 
template <typename T>
void foo(T begin, std::reverse_iterator<T> end)
{
  foo(begin, end.base());
}
 
template <typename T>
void foo(std::reverse_iterator<T> begin, T end)
{
  foo(begin, std::reverse_iterator<T>(end));
}
 
int main()
{
  std::vector<int> v { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
  foo(v.begin(), v.end()); std::cout << std::endl;
  foo(v.begin(), v.rbegin()); std::cout << std::endl;
  foo(v.rbegin(), v.begin()); std::cout << std::endl;
  foo(v.rbegin(), v.rend()); std::cout << std::endl;
}
 

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