Language: C++

//AnkitCode99 here....
//every ups and downs matter!

#include<bits/stdc++.h>

#define endl "\n"
typedef long long int ll;
#define MOD 1000000007
#define pll pair<ll,ll>
#define pb push_back
//max xor btw range of two numbers..
#define max_XOR(a,b) (1 << int(log2(a ^ b) + 1)) - 1
#define vl vector<ll>
#define inf ll(1e18)
#define all(v) v.begin(),v.end()
#define Ryuga ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define rep(i,a,b) for(long long int i=a;i<b;i++)
#define nrep(i,a,b) for(long long int i=a;i>=b;i--)
#define ceil(a,b) a/b+((a%b ==0 )?0:1)

using namespace std;

const ll sz=100005;
const ll szz=1000006;

int main()
{
    Ryuga;
    

    ll t;
    cin>>t;
    set<ll> st;
    while(t--)
    {
        string s;
        cin>>s;
        st.insert(s);
    }
    cout<<s.size();
    
}//Goodbye...

Compiler output:
a.cc: In function 'int main()':
a.cc:38:18: error: no matching function for call to 'std::set<long long int>::insert(std::string&)'
   38 |         st.insert(s);
      |         ~~~~~~~~~^~~
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:4:
/usr/include/c++/14/bits/stl_set.h:568:9: note: candidate: 'template<class _InputIterator> void std::set<_Key, _Compare, _Alloc>::insert(_InputIterator, _InputIterator) [with _Key = long long int; _Compare = std::less<long long int>; _Alloc = std::allocator<long long int>]'
  568 |         insert(_InputIterator __first, _InputIterator __last)
      |         ^~~~~~
/usr/include/c++/14/bits/stl_set.h:568:9: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_set.h:511:7: note: candidate: 'std::pair<typename std::_Rb_tree<_Key, _Key, std::_Identity<_Tp>, _Compare, typename __gnu_cxx::__alloc_traits<_Alloc>::rebind<_Key>::other>::const_iterator, bool> std::set<_Key, _Compare, _Alloc>::insert(const value_type&) [with _Key = long long int; _Compare = std::less<long long int>; _Alloc = std::allocator<long long int>; typename std::_Rb_tree<_Key, _Key, std::_Identity<_Tp>, _Compare, typename __gnu_cxx::__alloc_traits<_Alloc>::rebind<_Key>::other>::const_iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::const_iterator; typename __gnu_cxx::__alloc_traits<_Alloc>::rebind<_Key>::other = std::allocator<long long int>; typename __gnu_cxx::__alloc_traits<_Alloc>::rebind<_Key> = __gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::rebind<long long int>; typename _Alloc::value_type = long long int; value_type = long long int]'
  511 |       insert(const value_type& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_set.h:511:32: note:   no known conversion for argument 1 from 'std::string' {aka 'std::__cxx11::basic_string<char>'} to 'const std::set<long long int>::value_type&' {aka 'const long long int&'}
  511 |       insert(const value_type& __x)
      |              ~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_set.h:520:7: note: candidate: 'std::pair<typename std::_Rb_tree<_Key, _Key, std::_Identity<_Tp>, _Compare, typename __gnu_cxx::__alloc_traits<_Alloc>::rebind<_Key>::other>::const_iterator, bool> std::set<_Key, _Compare, _Alloc>::insert(value_type&&) [with _Key = long long int; _Compare = std::less<long long int>; _Alloc = std::allocator<long long int>; typename std::_Rb_tree<_Key, _Key, std::_Identity<_Tp>, _Compare, typename __gnu_cxx::__alloc_traits<_Alloc>::rebind<_Key>::other>::const_iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::const_iterator; typename __gnu_cxx::__alloc_traits<_Alloc>::rebind<_Key>::other = std::allocator<long long int>; typename __gnu_cxx::__alloc_traits<_Alloc>::rebind<_Key> = __gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::rebind<long long int>; typename _Alloc::value_type = long long int; value_type = long long int]'
  520 |       insert(value_type&& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_set.h:520:27: note:   no known conversion for argument 1 from 'std::string' {aka 'std::__cxx11::basic_string<char>'} to 'std::set<long long int>::value_type&&' {aka 'long long int&&'}
  520 |       insert(value_type&& __x)
      |              ~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_set.h:548:7: note: candidate: 'std::set<_Key, _Compare, _Alloc>::iterator std::set<_Key, _Compare, _Alloc>::insert(const_iterator, const value_type&) [with _Key = long long int; _Compare = std::less<long long int>; _Alloc = std::allocator<long long int>; iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::const_iterator; const_iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::const_iterator; value_type = long long int]'
  548 |       insert(const_iterator __position, const value_type& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_set.h:548:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_set.h:553:7: note: candidate: 'std::set<_Key, _Compare, _Alloc>::iterator std::set<_Key, _Compare, _Alloc>::insert(const_iterator, value_type&&) [with _Key = long long int; _Compare = std::less<long long int>; _Alloc = std::allocator<long long int>; iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::const_iterator; const_iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::const_iterator; value_type = long long int]'
  553 |       insert(const_iterator __position, value_type&& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_set.h:553:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_set.h:580:7: note: candidate: 'void std::set<_Key, _Compare, _Alloc>::insert(std::initializer_list<_Tp>) [with _Key = long long int; _Compare = std::less<long long int>; _Alloc = std::allocator<long long int>]'
  580 |       insert(initializer_list<value_type> __l)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_set.h:580:43: note:   no known conversion for argument 1 from 'std::string' {aka 'std::__cxx11::basic_string<char>'} to 'std::initializer_list<long long int>'
  580 |       insert(initializer_list<value_type> __l)
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_set.h:600:7: note: candidate: 'std::set<_Key, _Compare, _Alloc>::insert_return_type std::set<_Key, _Compare, _Alloc>::insert(node_type&&) [with _Key = long long int; _Compare = std::less<long long int>; _Alloc = std::allocator<long long int>; insert_return_type = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::insert_return_type; node_type = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::node_type]'
  600 |       insert(node_type&& __nh)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_set.h:600:26: note:   no known conversion for argument 1 from 'std::string' {aka 'std::__cxx11::basic_string<char>'} to 'std::set<long long int>::node_type&&' {aka 'std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::node_type&&'}
  600 |       insert(node_type&& __nh)
      |              ~~~~~~~~~~~~^~~~
/usr/include/c++/14/bits/stl_set.h:605:7: note: candidate: 'std::set<_Key, _Compare, _Alloc>::iterator std::set<_Key, _Compare, _Alloc>::insert(const_iterator, node_type&&) [with _Key = long long int; _Compare = std::less<long long int>; _Alloc = std::allocator<long long int>; iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::const_iterator; const_iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::const_iterator; node_type = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, std::less<long long int>, std::allocator<long long int> >::node_type]'
  605 |       insert(const_iterator __hint, node_type&& __nh)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_set.h:605:7: note:   candidate expects 2 arguments, 1 provided
a.cc:40:11: error: 's' was not declared in this scope; did you mean 'st'?
   40 |     cout<<s.size();
      |           ^
      |           st