Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:20:10: error: no match for ‘operator-’ (operand types are ‘std::set<int>::iterator {aka std::_Rb_tree_const_iterator<int>}’ and ‘std::set<int>::iterator {aka std::_Rb_tree_const_iterator<int>}’) q=it1-it2; ^ user.cpp:20:10: note: candidates are: In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0, from /usr/include/c++/4.8/bits/stl_tree.h:61, from /usr/include/c++/4.8/set:60, from user.cpp:2: /usr/include/c++/4.8/bits/stl_iterator.h:327:5: note: template<class _Iterator> typename std::reverse_iterator<_Iterator>::difference_type std::operator-(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&) operator-(const reverse_iterator<_Iterator>& __x, ^ /usr/include/c++/4.8/bits/stl_iterator.h:327:5: note: template argument deduction/substitution failed: user.cpp:20:11: note: ‘std::set<int>::iterator {aka std::_Rb_tree_const_iterator<int>}’ is not derived from ‘const std::reverse_iterator<_Iterator>’ q=it1-it2; ^ In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0, from /usr/include/c++/4.8/bits/stl_tree.h:61, from /usr/include/c++/4.8/set:60, from user.cpp:2: /usr/include/c++/4.8/bits/stl_iterator.h:379:5: note: template<class _IteratorL, class _IteratorR> decltype ((__y.base() - __x.base())) std::operator-(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&) operator-(const reverse_iterator<_IteratorL>& __x, ^ /usr/include/c++/4.8/bits/stl_iterator.h:379:5: note: template argument deduction/substitution failed: user.cpp:20:11: note: ‘std::set<int>::iterator {aka std::_Rb_tree_const_iterator<int>}’ is not derived from ‘const std::reverse_iterator<_Iterator>’ q=it1-it2; ^ In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0, from /usr/include/c++/4.8/bits/stl_tree.h:61, from /usr/include/c++/4.8/set:60, from user.cpp:2: /usr/include/c++/4.8/bits/stl_iterator.h:1104:5: note: template<class _IteratorL, class _IteratorR> decltype ((__x.base() - __y.base())) std::operator-(const std::move_iterator<_Iterator>&, const std::move_iterator<_IteratorR>&) operator-(const move_iterator<_IteratorL>& __x, ^ /usr/include/c++/4.8/bits/stl_iterator.h:1104:5: note: template argument deduction/substitution failed: user.cpp:20:11: note: ‘std::set<int>::iterator {aka std::_Rb_tree_const_iterator<int>}’ is not derived from ‘const std::move_iterator<_Iterator>’ q=it1-it2; ^ In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0, from /usr/include/c++/4.8/bits/stl_tree.h:61, from /usr/include/c++/4.8/set:60, from user.cpp:2: /usr/include/c++/4.8/bits/stl_iterator.h:1111:5: note: template<class _Iterator> decltype ((__x.base() - __y.base())) std::operator-(const std::move_iterator<_Iterator>&, const std::move_iterator<_Iterator>&) operator-(const move_iterator<_Iterator>& __x, ^ /usr/include/c++/4.8/bits/stl_iterator.h:1111:5: note: template argument deduction/substitution failed: user.cpp:20:11: note: ‘std::set<int>::iterator {aka std::_Rb_tree_const_iterator<int>}’ is not derived from ‘const std::move_iterator<_Iterator>’ q=it1-it2; ^ user.cpp:26:14: error: no match for ‘operator-’ (operand types are ‘std::set<int>::iterator {aka std::_Rb_tree_const_iterator<int>}’ and ‘std::set<int>::iterator {aka std::_Rb_tree_const_iterator<int>}’)