Language: C++

#include <bits/stdc++.h>
using namespace std;

int main() {
	int n;
	cin >> n;

	set<char> s;

	for(int i = 0; i < n; ++i) {
		char c;
		cin >> c;
		s.insert(c);
	}

	if(s.find("Y") != s.end()) cout << "Four" << endl;
	else cout << "Three" << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:16:18: error: no matching function for call to 'std::set<char>::find(const char [2])'
   16 |         if(s.find("Y") != s.end()) cout << "Four" << endl;
      |            ~~~~~~^~~~~
In file included from /usr/include/c++/14/set:63,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:158,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_set.h:796:7: note: candidate: 'std::set<_Key, _Compare, _Alloc>::iterator std::set<_Key, _Compare, _Alloc>::find(const key_type&) [with _Key = char; _Compare = std::less<char>; _Alloc = std::allocator<char>; iterator = std::_Rb_tree<char, char, std::_Identity<char>, std::less<char>, std::allocator<char> >::const_iterator; key_type = char]' (near match)
  796 |       find(const key_type& __x)
      |       ^~~~
/usr/include/c++/14/bits/stl_set.h:796:7: note:   conversion of argument 1 would be ill-formed:
a.cc:16:19: error: invalid conversion from 'const char*' to 'std::set<char>::key_type' {aka 'char'} [-fpermissive]
   16 |         if(s.find("Y") != s.end()) cout << "Four" << endl;
      |                   ^~~
      |                   |
      |                   const char*
/usr/include/c++/14/bits/stl_set.h:800:7: note: candidate: 'std::set<_Key, _Compare, _Alloc>::const_iterator std::set<_Key, _Compare, _Alloc>::find(const key_type&) const [with _Key = char; _Compare = std::less<char>; _Alloc = std::allocator<char>; const_iterator = std::_Rb_tree<char, char, std::_Identity<char>, std::less<char>, std::allocator<char> >::const_iterator; key_type = char]' (near match)
  800 |       find(const key_type& __x) const
      |       ^~~~
/usr/include/c++/14/bits/stl_set.h:800:7: note:   conversion of argument 1 would be ill-formed:
a.cc:16:19: error: invalid conversion from 'const char*' to 'std::set<char>::key_type' {aka 'char'} [-fpermissive]
   16 |         if(s.find("Y") != s.end()) cout << "Four" << endl;
      |                   ^~~
      |                   |
      |                   const char*
/usr/include/c++/14/bits/stl_set.h:806:9: note: candidate: 'template<class _Kt> decltype (std::set<_Key, _Compare, _Alloc>::iterator{((std::set<_Key, _Compare, _Alloc>*)this)->std::set<_Key, _Compare, _Alloc>::_M_t._M_find_tr(__x)}) std::set<_Key, _Compare, _Alloc>::find(const _Kt&) [with _Key = char; _Compare = std::less<char>; _Alloc = std::allocator<char>]'
  806 |         find(const _Kt& __x)
      |         ^~~~
/usr/include/c++/14/bits/stl_set.h:806:9: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_set.h: In substitution of 'template<class _Kt> decltype (std::set<char>::iterator{((std::set<char>*)this)->std::set<char>::_M_t.std::_Rb_tree<char, char, std::_Identity<char>, std::less<char>, std::allocator<char> >::_M_find_tr(__x)}) std::set<char>::find(const _Kt&) [with _Kt = char [2]]':
a.cc:16:11:   required from here
   16 |         if(s.find("Y") != s.end()) cout << "Four" << endl;
      |            ~~~~~~^~~~~
/usr/include/c++/14/bits/stl_set.h:807:45: error: no matching function for call to 'std::_Rb_tree<char, char, std::_Identity<char>, std::less<char>, std::allocator<char> >::_M_find_tr(const char [2])'
  807 |         -> decltype(iterator{_M_t._M_find_tr(__x)})
      |                              ~~~~~~~~~~~~~~~^~~~~
In file included from /usr/include/c++/14/map:62,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:152:
/usr/include/c++/14/bits/stl_tree.h:1291:9: note: candidate: 'template<class _Kt, class _Req> std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_find_tr(const _Kt&) [with _Req = _Kt; _Key = char; _Val = char; _KeyOfValue = std::_Identity<char>; _Compare = std::less<char>; _Alloc = std::allocator<char>]'
 1291 |         _M_find_tr(const _Kt& __k)
      |         ^~~~~~~~~~
/usr/include/c++/14/bits/stl_tree.h:1291:9: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/14/string:49,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/stl_function.h: In substitution of 'template<class _Func, class _SfinaeType> using std::__has_is_transparent_t = typename std::__has_is_transparent<_Func, _SfinaeType>::type [with _Func = std::less<char>; _SfinaeType = char [2]]':
/usr/include/c++/14/bits/stl_tree.h:1289:9:   required by substitution of 'template<class _Kt> decltype (std::set<char>::iterator{((std::set<char>*)this)->std::set<char>::_M_t.std::_Rb_tree<char, char, std::_Identity<char>, std::less<char>, std::allocator<char> >::_M_find_tr(__x)}) std::set<char>::find(const _Kt&) [with _Kt = char [2]]'
 1289 |                typename _Req = __has_is_transparent_t<_Compare, _Kt>>
      |                ^~~~~~~~
a.cc:16:11:   required from here
   16 |         if(s.find("Y") != s.end()) cout << "Four" << endl;
      |            ~~~~~~^~~~~
/usr/include/c++/14/bits/stl_function.h:1427:11: error: no type named 'type' in 'struct std::__has_is_transparent<std::less<char>, char [2], void>'
 1427 |     using __has_is_transparent_t
      |           ^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_set.h: In substitution of 'template<class _Kt> decltype (std::set<char>::iterator{((std::set<char>*)this)->std::set<char>::_M_t.std::_Rb_tree<char, char, std::_Identity<char>, std::less<char>, std::allocator<char> >::_M_find_tr(__x)}) std::set<char>::find(const _Kt&) [with _Kt = char [2]]':
a.cc:16:11:   required from here
   16 |         if(s.find("Y") != s.end()) cout << "Four" << endl;
      |            ~~~~~~^~~~~
/usr/include/c++/14/bits/stl_tree.h:1300:9: note: candidate: 'template<class _Kt, class _Req> std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::const_iterator std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_find_tr(const _Kt&) const [with _Req = _Kt; _Key = char; _Val = char; _KeyOfValue = std::_Identity<char>; _Compare = std::less<char>; _Alloc = std::allocator<char>]'
 1300 |         _M_find_tr(const _Kt& __k) const
      |         ^~~~~~~~~~
/usr/include/c++/14/bits/stl_tree.h:1300:9: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_set.h:806:9: error: no matching function for call to 'std::_Rb_tree_const_iterator<char>::_Rb_tree_const_iterator(<brace-enclosed initializer list>)'
  806 |         find(const _Kt& __x)
      |         ^~~~
/usr/include/c++/14/bits/stl_tree.h:346:7: note: candidate: 'std::_Rb_tree_const_iterator<_Tp>::_Rb_tree_const_iterator(const iterator&) [with _Tp = char; iterator = std::_Rb_tree_const_iterator<char>::iterator]'
  346 |       _Rb_tree_const_iterator(const iterator& __it) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_tree.h:346:7: note:   conversion of argument 1 would be ill-formed:
/usr/include/c++/14/bits/stl_tree.h:343:7: note: candidate: 'std::_Rb_tree_const_iterator<_Tp>::_Rb_tree_const_iterator(_Base_ptr) [with _Tp = char; _Base_ptr = const std::_Rb_tree_node_base*]'
  343 |       _Rb_tree_const_iterator(_Base_ptr __x) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_tree.h:343:7: note:   conversion of argument 1 would be ill-formed:
/usr/include/c++/14/bits/stl_tree.h:339:7: note: candidate: 'std::_Rb_tree_const_iterator<_Tp>::_Rb_tree_const_iterator() [with _Tp = char]'
  339 |       _Rb_tree_const_iterator() _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_tree.h:339:7: note:   candidate expects 0 arguments, 1 provided
/usr/include/c++/14/bits/stl_tree.h:324:12: note: candidate: 'constexpr std::_Rb_tree_const_iterator<char>::_Rb_tree_const_iterator(const std::_Rb_tree_const_iterator<char>&)'
  324 |     struct _Rb_tree_const_iterator
      |            ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_tree.h:324:12: note:   conversion of argument 1 would be ill-formed:
/usr/include/c++/14/bits/stl_tree.h:324:12: note: candidate: 'constexpr std::_Rb_tree_const_iterator<char>::_Rb_tree_const_iterator(std::_Rb_tree_const_iterator<char>&&)'
/usr/include/c++/14/bits/stl_tree.h:324:12: note:   conversion of argument 1 would be ill-formed:
/usr/include/c++/14/bits/stl_set.h:812:9: note: candidate: 'template<class _Kt> decltype (std::set<_Key, _Compare, _Alloc>::const_iterator{((const std::set<_Key, _Compare, _Alloc>*)this)->std::set<_Key, _Compare, _Alloc>::_M_t._M_find_tr(__x)}) std::set<_Key, _Compare, _Alloc>::find(const _Kt&) const [with _Key = char; _Compare = std::less<char>; _Alloc = std::allocator<char>]'
  812 |         find(const _Kt& __x) const
      |         ^~~~
/usr/include/c++/14/bits/stl_set.h:812:9: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_set.h: In substitution of 'template<class _Kt> decltype (std::set<char>::const_iterator{((const std::set<char>*)this)->std::set<char>::_M_t.std::_Rb_tree<char, char, std::_Identity<char>, std::less<char>, std::allocator<char> >::_M_find_tr(__x)}) std::set<char>::find(const _Kt&) const [with _Kt = char [2]]':
a.cc:16:11:   required from here
   16 |         if(s.find("Y") != s.end()) cout << "Four" << endl;
      |            ~~~~~~^~~~~
/usr/include/c++/14/bits/stl_set.h:813:51: error: no matching function for call to 'std::_Rb_tree<char, char, std::_Identity<char>, std::less<char>, std::allocator<char> >::_M_find_tr(const char [2]) const'
  813 |         -> decltype(const_iterator{_M_t._M_find_tr(__x)})
      |                                    ~~~~~~~~~~~~~~~^~~~~
/usr/include/c++/14/bits/stl_tree.h:1291:9: note: candidate: 'template<class _Kt, class _Req> std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_find_tr(const _Kt&) [with _Req = _Kt; _Key = char; _Val = char; _KeyOfValue = std::_Identity<char>; _Compare = std::less<char>; _Alloc = std::allocator<char>]'
 1291 |         _M_find_tr(const _Kt& __k)
      |         ^~~~~~~~~~
/usr/include/c++/14/bits/stl_tree.h:1291:9: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_tree.