Language: C++

    #include<iostream>
    #include<stdio.h>
    //#include <bits/stdc++.h>
    #include<vector>
    #include<float.h>
    #include<iomanip>
    #include<algorithm>
    #include<string>
    #include<cstring>
    #include<math.h>
    #include<cmath>
    #include<sstream>
    #include<set>
    #include<map>
    #include<queue>
    #include <cassert>
    #include <cmath>
    #include<cstdint>

    #define INF 1e7
    #define rep(i,n)for(int i=0;(i)<(int)(n);i++)
    #define REP(i,a,b)for(int i=(int)(a);(i)<=(int)(b);i++)
    #define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
    #define vec(type,n) vector<type>(n)
    #define vvec(m,n) vector<vector<int>> (int(m),vector<int>(n))

    using namespace std;
    using ll = long long;
    using Graph = vector<vector<int>>;
    using P = pair<int,int>;

    int main(){
        string s;
        map<string,int>mp;
        rep(i,s.size()){
            mp[s[i]]++;
        }
        for(auto m:mp){
            if(m.second!=2){cout<<"No";return 0;}
        }
        cout<<"Yes";
    }
    


Compiler output:
a.cc: In function 'int main()':
a.cc:36:15: error: no match for 'operator[]' (operand types are 'std::map<std::__cxx11::basic_string<char>, int>' and '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'})
   36 |             mp[s[i]]++;
      |               ^
In file included from /usr/include/c++/14/map:63,
                 from a.cc:14:
/usr/include/c++/14/bits/stl_map.h:504:7: note: candidate: 'std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const key_type&) [with _Key = std::__cxx11::basic_string<char>; _Tp = int; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> >; mapped_type = int; key_type = std::__cxx11::basic_string<char>]'
  504 |       operator[](const key_type& __k)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_map.h:504:34: note:   no known conversion for argument 1 from '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'} to 'const std::map<std::__cxx11::basic_string<char>, int>::key_type&' {aka 'const std::__cxx11::basic_string<char>&'}
  504 |       operator[](const key_type& __k)
      |                  ~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_map.h:524:7: note: candidate: 'std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](key_type&&) [with _Key = std::__cxx11::basic_string<char>; _Tp = int; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> >; mapped_type = int; key_type = std::__cxx11::basic_string<char>]'
  524 |       operator[](key_type&& __k)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_map.h:524:29: note:   no known conversion for argument 1 from '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'} to 'std::map<std::__cxx11::basic_string<char>, int>::key_type&&' {aka 'std::__cxx11::basic_string<char>&&'}
  524 |       operator[](key_type&& __k)
      |                  ~~~~~~~~~~~^~~