Language: C++

#include <bits/stdc++.h>
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long int ll;
typedef unsigned long long int ull;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> o_set; 

#define     int                 ll
#define     pb                  push_back
#define     mp                  make_pair
#define     xx                  first
#define     yy                  second    
#define     all(a)              a.begin(),a.end()
#define     vi                  vector<int>
#define     vpi                 vector<pii>
#define     pii                 pair<int, int>
#define     present(DT, val)    (DT.find(val) != DT.end()) //for set and map
#define     cpresent(DT, val)   (find(all(DT),val) != DT.end()) //vectors
#define     input               "/home/pollution/Desktop/WorkSpace/C++/Files/input.txt"
#define     output              "/home/pollution/Desktop/WorkSpace/C++/Files/output1.txt"
#define     error               "/home/pollution/Desktop/WorkSpace/C++/Files/error.txt"
#define     IO()                ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define     INF                 2e18
#define     MOD                 1000000007
#define     clr(x)              memset(x, 0, sizeof(x))
#define     init(x, a)          memset(x, a, sizeof(x))
#define     out(a)              for (auto i: a) cout<<i<<' '; cout<<'\n'
#define     cpy(a,b)            memcpy(a,b,sizeof(b))
#define     is(a)               to_string(a)
#define     ci(a,c)             a-c
#define     db(i)               cout<<"point :"<<i<<'\n';
#define     setd(val,n)         cout<<fixed<<setprecision(n)<<val<<'\n'

void solve(){
    int n; cin>>n;
    unordered_map<string, int> hmap;
    string s;
    for(int i = 0; i < n; ++i){
    	cin>>s;
    	hmap[s]++;
    }
    cout<hmap.size()<<'\n';
}

signed main() { 
    IO();
    
    int t=1;
    cin>>t;
    while(t--) solve();
    return 0; 
}

Compiler output:
a.cc: In function 'void solve()':
a.cc:45:9: error: no match for 'operator<' (operand types are 'std::ostream' {aka 'std::basic_ostream<char>'} and 'std::unordered_map<std::__cxx11::basic_string<char>, long long int>::size_type' {aka 'long unsigned int'})
   45 |     cout<hmap.size()<<'\n';
      |     ~~~~^~~~~~~~~~~~~~~~~~
      |     |               |
      |     |               std::unordered_map<std::__cxx11::basic_string<char>, long long int>::size_type {aka long unsigned int}
      |     std::ostream {aka std::basic_ostream<char>}
a.cc:45:9: note: candidate: 'operator<(int, std::unordered_map<std::__cxx11::basic_string<char>, long long int>::size_type {aka long unsigned int})' (built-in)
   45 |     cout<hmap.size()<<'\n';
      |     ~~~~^~~~~~~~~~~~~~~~~~
a.cc:45:9: note:   no known conversion for argument 1 from 'std::ostream' {aka 'std::basic_ostream<char>'} to 'int'
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181,
                 from a.cc:1:
/usr/include/c++/14/bits/regex.h:1143:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1143 |     operator<(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1143:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/bits/regex.h:1224:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator<(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1224 |     operator<(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1224:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/bits/regex.h:1317:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator<(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1317 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1317:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/bits/regex.h:1391:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1391 |     operator<(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1391:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'std::unordered_map<std::__cxx11::basic_string<char>, long long int>::size_type' {aka 'long unsigned int'}
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/bits/regex.h:1485:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1485 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1485:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/bits/regex.h:1560:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1560 |     operator<(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1560:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'std::unordered_map<std::__cxx11::basic_string<char>, long long int>::size_type' {aka 'long unsigned int'}
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/bits/regex.h:1660:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1660 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1660:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_pair.h:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'const std::pair<_T1, _T2>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/string_view:673:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  673 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:673:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/string_view:680:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  680 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:680:5: note:   template argument deduction/substitution failed:
a.cc:45:23: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   45 |     cout<hmap.size()<<'\n';
      |                       ^~~~
/usr/include/c++/14/string_view:688:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  688 |     operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr