Eroare de compilare: /usr/include/c++/4.2/bits/stl_algo.h: In function 'const _Tp& std::__median(const _Tp&, const _Tp&, const _Tp&) [with _Tp = ev]': /usr/include/c++/4.2/bits/stl_algo.h:2758: instantiated from 'void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<ev*, std::vector<ev, std::allocator<ev> > >, _Size = int]' /usr/include/c++/4.2/bits/stl_algo.h:2829: instantiated from 'void std::sort(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<ev*, std::vector<ev, std::allocator<ev> > >]' user.cpp:110: instantiated from here /usr/include/c++/4.2/bits/stl_algo.h:91: error: passing 'const ev' as 'this' argument of 'bool ev::operator<(const ev&)' discards qualifiers /usr/include/c++/4.2/bits/stl_algo.h:92: error: passing 'const ev' as 'this' argument of 'bool ev::operator<(const ev&)' discards qualifiers /usr/include/c++/4.2/bits/stl_algo.h:94: error: passing 'const ev' as 'this' argument of 'bool ev::operator<(const ev&)' discards qualifiers /usr/include/c++/4.2/bits/stl_algo.h:98: error: passing 'const ev' as 'this' argument of 'bool ev::operator<(const ev&)' discards qualifiers /usr/include/c++/4.2/bits/stl_algo.h:100: error: passing 'const ev' as 'this' argument of 'bool ev::operator<(const ev&)' discards qualifiers