Why this error occurs : binary '-' : 'std::_list_iterator<_mylist>' does not define this operator or a conversion to a type acceptable to the predefined operator?

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C++

hello, I wrote the following code to sort the map in c++ by the second value of tuples(instead of the first value). but, it gives me the error :" binary '-' : 'std::_List_iterator<_Mylist>' does not define this operator or a conversion to a type acceptable to the predefined operator" and the position of the error is in the header "algorithm.h". why does it occur?

<pre>template<class T>
struct less_second
: std::binary_function<T,T,bool>
{
   inline bool operator()(const T& lhs, const T& rhs)
   {
      return lhs.second < rhs.second;
   }
};

typedef std::pair<int,int> data_t;
		std::list<data_t> vec(groups.begin(), groups.end());
		std::sort(vec.begin(), vec.end(), less_second<data_t>());

What I have tried:

I used the code from:STL std::map and sorting using value_compare - General Programming - GameDev.net[^]