Language: C++

#include<bits/stdc++.h>
int main(){
  int n;
  while(cin>>n&&n){
    m=0,an=0;
    memset(D,0,sizeof(D));
    string s;
    map<char,int> c;
    vector<char> v;
    for(int i=0;i<n;i++){
      cin>>s;
      int l=1;
      if(i==n-1)l=-1;
      for(int j=s.size()-1,k=1;j>=0;j--,k*=10){
	if(j==0&&s.size()!=1)v.push_back(s[j]);
	if(c.find(s[j])==c.end())c[s[j]]=l*k;
	else c[s[j]]+=l*k;
      }
    }
    map<char,int>::iterator it;
    for(it=c.begin();it!=c.end();it++){
      for(int i=0;i<v.size();i++)
	if((*it).first==v[i])D[m]=1;
      kei[m++]=(*it).second;
    }
    dfs(0,0);
    cout<<an<<endl;
  }
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:4:9: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    4 |   while(cin>>n&&n){
      |         ^~~
      |         std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:5:5: error: 'm' was not declared in this scope
    5 |     m=0,an=0;
      |     ^
a.cc:5:9: error: 'an' was not declared in this scope; did you mean 'n'?
    5 |     m=0,an=0;
      |         ^~
      |         n
a.cc:6:12: error: 'D' was not declared in this scope
    6 |     memset(D,0,sizeof(D));
      |            ^
a.cc:7:5: error: 'string' was not declared in this scope
    7 |     string s;
      |     ^~~~~~
a.cc:7:5: note: suggested alternatives:
In file included from /usr/include/c++/14/string:41,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:8:5: error: 'map' was not declared in this scope
    8 |     map<char,int> c;
      |     ^~~
a.cc:8:5: note: suggested alternatives:
In file included from /usr/include/c++/14/map:63,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:152:
/usr/include/c++/14/bits/stl_map.h:102:11: note:   'std::map'
  102 |     class map
      |           ^~~
/usr/include/c++/14/map:89:13: note:   'std::pmr::map'
   89 |       using map
      |             ^~~
a.cc:8:9: error: expected primary-expression before 'char'
    8 |     map<char,int> c;
      |         ^~~~
a.cc:9:5: error: 'vector' was not declared in this scope
    9 |     vector<char> v;
      |     ^~~~~~
a.cc:9:5: note: suggested alternatives:
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:
/usr/include/c++/14/bits/stl_vector.h:428:11: note:   'std::vector'
  428 |     class vector : protected _Vector_base<_Tp, _Alloc>
      |           ^~~~~~
/usr/include/c++/14/vector:93:13: note:   'std::pmr::vector'
   93 |       using vector = std::vector<_Tp, polymorphic_allocator<_Tp>>;
      |             ^~~~~~
a.cc:9:12: error: expected primary-expression before 'char'
    9 |     vector<char> v;
      |            ^~~~
a.cc:11:12: error: 's' was not declared in this scope
   11 |       cin>>s;
      |            ^
a.cc:14:41: error: 'k' was not declared in this scope
   14 |       for(int j=s.size()-1,k=1;j>=0;j--,k*=10){
      |                                         ^
a.cc:15:30: error: 'v' was not declared in this scope
   15 |         if(j==0&&s.size()!=1)v.push_back(s[j]);
      |                              ^
a.cc:16:12: error: 'c' was not declared in this scope
   16 |         if(c.find(s[j])==c.end())c[s[j]]=l*k;
      |            ^
a.cc:20:9: error: expected primary-expression before 'char'
   20 |     map<char,int>::iterator it;
      |         ^~~~
a.cc:21:9: error: 'it' was not declared in this scope; did you mean 'int'?
   21 |     for(it=c.begin();it!=c.end();it++){
      |         ^~
      |         int
a.cc:21:12: error: 'c' was not declared in this scope
   21 |     for(it=c.begin();it!=c.end();it++){
      |            ^
a.cc:22:21: error: 'v' was not declared in this scope
   22 |       for(int i=0;i<v.size();i++)
      |                     ^
a.cc:24:7: error: 'kei' was not declared in this scope
   24 |       kei[m++]=(*it).second;
      |       ^~~
a.cc:26:5: error: 'dfs' was not declared in this scope; did you mean 'ffs'?
   26 |     dfs(0,0);
      |     ^~~
      |     ffs
a.cc:27:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   27 |     cout<<an<<endl;
      |     ^~~~
      |     std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:27:15: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   27 |     cout<<an<<endl;
      |               ^~~~
      |               std::endl
In file included from /usr/include/c++/14/istream:41,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~