Language: C++

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

int alphabet_pos(char c){
  if('a' <= c && c <= 'z') return (c-'a'+1);
  return -1;
}
 
int main() {
  vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
  vector<int> a,d;
  string S;
  cin >> S;
  for(i=0;i<26;i++){
    a[i]=alphabet_pos(S[i])
  }
  sort(data.begin(),data.end());
  if(S.length()==0){
    if(S=="zyxwvutsrqponmlkjihgfedcba"){
      cout << -1 <<endl;
    }
    else{
      for(i=0;true;i++){
        if(i==a[i]-1){
          cout << c[i];
        }
        else{
          cout << c[i];
          break;
        }
      }
    }
  }
  else{
    for(i=0;true;i++){
        if(i==a[i]-1)continue;
        else{
          d=i;
          break;
        }
    }
    cout << S << c[d];
}

Compiler output:
a.cc: In function 'int main()':
a.cc:10:18: error: 'a' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                  ^
a.cc:10:20: error: 'b' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                    ^
a.cc:10:24: error: 'd' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                        ^
a.cc:10:26: error: 'e' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                          ^
a.cc:10:28: error: 'f' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                            ^
a.cc:10:30: error: 'g' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                              ^
a.cc:10:32: error: 'h' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                ^
a.cc:10:34: error: 'i' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                  ^
a.cc:10:36: error: 'j' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                    ^
a.cc:10:38: error: 'k' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                      ^
a.cc:10:40: error: 'l' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                        ^
a.cc:10:42: error: 'm' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                          ^
a.cc:10:44: error: 'n' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                            ^
a.cc:10:46: error: 'o' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                              ^
a.cc:10:48: error: 'p' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                ^
a.cc:10:50: error: 'q' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                  ^
a.cc:10:52: error: 'r' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                    ^
a.cc:10:54: error: 's' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                      ^
a.cc:10:56: error: 't' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                        ^
a.cc:10:58: error: 'u' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                          ^
a.cc:10:60: error: 'v' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                            ^
a.cc:10:62: error: 'w' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                              ^
a.cc:10:64: error: 'x' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                                ^
a.cc:10:66: error: 'y' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                                  ^
a.cc:10:68: error: 'z' was not declared in this scope
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                                    ^
a.cc:10:69: error: no matching function for call to 'std::vector<char>::vector(<brace-enclosed initializer list>)'
   10 |   vector<char> c{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}
      |                                                                     ^
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_vector.h:707:9: note: candidate: 'template<class _InputIterator, class> std::vector<_Tp, _Alloc>::vector(_InputIterator, _InputIterator, const allocator_type&) [with <template-parameter-2-2> = _InputIterator; _Tp = char; _Alloc = std::allocator<char>]'
  707 |         vector(_InputIterator __first, _InputIterator __last,
      |         ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:707:9: note:   candidate expects 3 arguments, 26 provided
/usr/include/c++/14/bits/stl_vector.h:678:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::initializer_list<_Tp>, const allocator_type&) [with _Tp = char; _Alloc = std::allocator<char>; allocator_type = std::allocator<char>]'
  678 |       vector(initializer_list<value_type> __l,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:678:7: note:   candidate expects 2 arguments, 26 provided
/usr/include/c++/14/bits/stl_vector.h:659:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, std::__type_identity_t<_Alloc>&) [with _Tp = char; _Alloc = std::allocator<char>; std::__type_identity_t<_Alloc> = std::allocator<char>]'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:659:7: note:   candidate expects 2 arguments, 26 provided
/usr/include/c++/14/bits/stl_vector.h:640:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::false_type) [with _Tp = char; _Alloc = std::allocator<char>; allocator_type = std::allocator<char>; std::false_type = std::false_type]'
  640 |       vector(vector&& __rv, const allocator_type& __m, false_type)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note:   candidate expects 3 arguments, 26 provided
/usr/include/c++/14/bits/stl_vector.h:635:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::true_type) [with _Tp = char; _Alloc = std::allocator<char>; allocator_type = std::allocator<char>; std::true_type = std::true_type]'
  635 |       vector(vector&& __rv, const allocator_type& __m, true_type) noexcept
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:635:7: note:   candidate expects 3 arguments, 26 provided
/usr/include/c++/14/bits/stl_vector.h:624:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&, std::__type_identity_t<_Alloc>&) [with _Tp = char; _Alloc = std::allocator<char>; std::__type_identity_t<_Alloc> = std::allocator<char>]'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:624:7: note:   candidate expects 2 arguments, 26 provided
/usr/include/c++/14/bits/stl_vector.h:620:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&) [with _Tp = char; _Alloc = std::allocator<char>]'
  620 |       vector(vector&&) noexcept = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note:   candidate expects 1 argument, 26 provided
/usr/include/c++/14/bits/stl_vector.h:601:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&) [with _Tp = char; _Alloc = std::allocator<char>]'
  601 |       vector(const vector& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:601:7: note:   candidate expects 1 argument, 26 provided
/usr/include/c++/14/bits/stl_vector.h:569:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const value_type&, const allocator_type&) [with _Tp = char; _Alloc = std::allocator<char>; size_type = long unsigned int; value_type = char; allocator_type = std::allocator<char>]'
  569 |       vector(size_type __n, const value_type& __value,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:569:7: note:   candidate expects 3 arguments, 26 provided
/usr/include/c++/14/bits/stl_vector.h:556:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const allocator_type&) [with _Tp = char; _Alloc = std::allocator<char>; size_type = long unsigned int; allocator_type = std::allocator<char>]'
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:7: note:   candidate expects 2 arguments, 26 provided
/usr/include/c++/14/bits/stl_vector.h:542:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const allocator_type&) [with _Tp = char; _Alloc = std::allocator<char>; allocator_type = std::allocator<char>]'
  542 |       vector(const allocator_type& __a) _GLIBCXX_NOEXCEPT
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note:   candidate expects 1 argument, 26 provided
/usr/include/c++/14/bits/stl_vector.h:531:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector() [with _Tp = char; _Alloc = std::allocator<char>]'
  531 |       vector() = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:531:7: note:   candidate expects 0 arguments, 26 provided
a.cc:11:3: error: expected ',' or ';' befor