Language: C++

#include <iostream>
#include <string>
#include <set>
using namespace std;
int main(void){
	set<string> st;
	string s,ss;
	int k,len,i,j;
	cin >> s;
	cin >> k;
	len = s.length();
	
	
	for(i = 'a'; i <= 'z'; i++){
		for(auto itr = st.begin(); itr != end(); itr++){
			if(itr == i){
				for(j = 0; j <= len; j++){
					for(k = 1; j+k <= len; k++)
						st.insert(s.substr(j,k));
				}			
			}
		}
		if(st.size() > k){
				i = 0;
				for(auto itr = st.begin(); itr != st.end(); ++itr) {
						i++;
						if(i == k)
							cout << *itr << endl;
				}
				return 0;
		}
	}
	
}


Compiler output:
a.cc: In function 'int main()':
a.cc:15:54: error: no matching function for call to 'end()'
   15 |                 for(auto itr = st.begin(); itr != end(); itr++){
      |                                                   ~~~^~
In file included from /usr/include/c++/14/bits/range_access.h:36,
                 from /usr/include/c++/14/string:53,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/initializer_list:99:5: note: candidate: 'template<class _Tp> constexpr const _Tp* std::end(initializer_list<_Tp>)'
   99 |     end(initializer_list<_Tp> __ils) noexcept
      |     ^~~
/usr/include/c++/14/initializer_list:99:5: note:   candidate expects 1 argument, 0 provided
/usr/include/c++/14/bits/range_access.h:74:5: note: candidate: 'template<class _Container> constexpr decltype (__cont.end()) std::end(_Container&)'
   74 |     end(_Container& __cont) -> decltype(__cont.end())
      |     ^~~
/usr/include/c++/14/bits/range_access.h:74:5: note:   candidate expects 1 argument, 0 provided
/usr/include/c++/14/bits/range_access.h:85:5: note: candidate: 'template<class _Container> constexpr decltype (__cont.end()) std::end(const _Container&)'
   85 |     end(const _Container& __cont) -> decltype(__cont.end())
      |     ^~~
/usr/include/c++/14/bits/range_access.h:85:5: note:   candidate expects 1 argument, 0 provided
/usr/include/c++/14/bits/range_access.h:106:5: note: candidate: 'template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::end(_Tp (&)[_Nm])'
  106 |     end(_Tp (&__arr)[_Nm]) noexcept
      |     ^~~
/usr/include/c++/14/bits/range_access.h:106:5: note:   candidate expects 1 argument, 0 provided
/usr/include/c++/14/bits/range_access.h:115:31: note: candidate: 'template<class _Tp> _Tp* std::end(valarray<_Tp>&)'
  115 |   template<typename _Tp> _Tp* end(valarray<_Tp>&) noexcept;
      |                               ^~~
/usr/include/c++/14/bits/range_access.h:115:31: note:   candidate expects 1 argument, 0 provided
/usr/include/c++/14/bits/range_access.h:116:37: note: candidate: 'template<class _Tp> const _Tp* std::end(const valarray<_Tp>&)'
  116 |   template<typename _Tp> const _Tp* end(const valarray<_Tp>&) noexcept;
      |                                     ^~~
/usr/include/c++/14/bits/range_access.h:116:37: note:   candidate expects 1 argument, 0 provided
a.cc:16:32: error: no match for 'operator==' (operand types are 'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' and 'int')
   16 |                         if(itr == i){
      |                            ~~~ ^~ ~
      |                            |      |
      |                            |      int
      |                            std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >
In file included from /usr/include/c++/14/iosfwd:42,
                 from /usr/include/c++/14/ios:40:
/usr/include/c++/14/bits/postypes.h:192:5: note: candidate: 'template<class _StateT> bool std::operator==(const fpos<_StateT>&, const fpos<_StateT>&)'
  192 |     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:192:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::fpos<_StateT>'
   16 |                         if(itr == i){
      |                                   ^
In file included from /usr/include/c++/14/string:43:
/usr/include/c++/14/bits/allocator.h:235:5: note: candidate: 'template<class _T1, class _T2> bool std::operator==(const allocator<_CharT>&, const allocator<_T2>&)'
  235 |     operator==(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/14/bits/allocator.h:235:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::allocator<_CharT>'
   16 |                         if(itr == i){
      |                                   ^
In file included from /usr/include/c++/14/string:48:
/usr/include/c++/14/bits/stl_iterator.h:441:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  441 |     operator==(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:441:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::reverse_iterator<_Iterator>'
   16 |                         if(itr == i){
      |                                   ^
/usr/include/c++/14/bits/stl_iterator.h:486:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  486 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::reverse_iterator<_Iterator>'
   16 |                         if(itr == i){
      |                                   ^
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1667 |     operator==(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::move_iterator<_IteratorL>'
   16 |                         if(itr == i){
      |                                   ^
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1737 |     operator==(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::move_iterator<_IteratorL>'
   16 |                         if(itr == i){
      |                                   ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/string:51:
/usr/include/c++/14/bits/stl_pair.h:1033:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1033 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1033:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::pair<_T1, _T2>'
   16 |                         if(itr == i){
      |                                   ^
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54:
/usr/include/c++/14/string_view:629:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  629 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:629:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   16 |                         if(itr == i){
      |                                   ^
/usr/include/c++/14/string_view:637:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  637 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:637:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   16 |                         if(itr == i){
      |                                   ^
/usr/include/c++/14/string_view:644:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  644 |     operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:644:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'int'
   16 |                         if(itr == i){
      |                                   ^
/usr/include/c++/14/bits/basic_string.h:3755:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3755 |     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3755:5: note:   template argument deduction/substitution failed:
a.cc:16:35: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   16 |                         if(itr