Language: C++

#include<iostream>
#include<map>
#include<cmath>
#include<vector>
using namespace std;
int main()
{
  map<string, int> M;
  int k;
  int a,b,c,d,e;
  vector<string> S = {"a","b","c","d","e"};
  cin >> a;
  cin >> b;
  cin >> c;
  cin >> d;
  cin >> e;
  M["a"] = a;
  M["b"] = b;
  M["c"] = c;
  M["d"] = d;
  M["e"] = e;
  for(char key : S){
    for(char  key_t : S){
      if(abs(M[key] - M[key_t]) > k){
        cout << ":(" << endl;
        break;
      }
    }
  }
  cout << "Yay!" << endl;
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:22:18: error: cannot convert 'std::__cxx11::basic_string<char>' to 'char' in initialization
   22 |   for(char key : S){
      |                  ^
a.cc:23:23: error: cannot convert 'std::__cxx11::basic_string<char>' to 'char' in initialization
   23 |     for(char  key_t : S){
      |                       ^
a.cc:24:15: error: no match for 'operator[]' (operand types are 'std::map<std::__cxx11::basic_string<char>, int>' and 'char')
   24 |       if(abs(M[key] - M[key_t]) > k){
      |               ^
In file included from /usr/include/c++/14/map:63,
                 from a.cc:2:
/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 '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 'char' to 'std::map<std::__cxx11::basic_string<char>, int>::key_type&&' {aka 'std::__cxx11::basic_string<char>&&'}
  524 |       operator[](key_type&& __k)
      |                  ~~~~~~~~~~~^~~
a.cc:24:24: error: no match for 'operator[]' (operand types are 'std::map<std::__cxx11::basic_string<char>, int>' and 'char')
   24 |       if(abs(M[key] - M[key_t]) > k){
      |                        ^
/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 '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 'char' to 'std::map<std::__cxx11::basic_string<char>, int>::key_type&&' {aka 'std::__cxx11::basic_string<char>&&'}
  524 |       operator[](key_type&& __k)
      |                  ~~~~~~~~~~~^~~