Language: C++

#include<iostream>
using std;
int main(){
	string o,e;cin>>o>>e;
  for(int i=0;i<min(o.size(),e.size());i++){
  	cout<<o[i]<<e[i];
  }
  if(o.size()>e.size())cout<<o.back();
  cout<<endl;
}

Compiler output:
a.cc:2:7: error: expected nested-name-specifier before 'std'
    2 | using std;
      |       ^~~
a.cc: In function 'int main()':
a.cc:4:9: error: 'string' was not declared in this scope
    4 |         string o,e;cin>>o>>e;
      |         ^~~~~~
a.cc:4:9: note: suggested alternatives:
In file included from /usr/include/c++/14/iosfwd:41,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
In file included from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44:
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:4:20: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    4 |         string o,e;cin>>o>>e;
      |                    ^~~
      |                    std::cin
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:4:25: error: 'o' was not declared in this scope
    4 |         string o,e;cin>>o>>e;
      |                         ^
a.cc:4:28: error: 'e' was not declared in this scope
    4 |         string o,e;cin>>o>>e;
      |                            ^
a.cc:5:17: error: 'min' was not declared in this scope; did you mean 'std::min'?
    5 |   for(int i=0;i<min(o.size(),e.size());i++){
      |                 ^~~
      |                 std::min
In file included from /usr/include/c++/14/string:51:
/usr/include/c++/14/bits/stl_algobase.h:281:5: note: 'std::min' declared here
  281 |     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
a.cc:6:9: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    6 |         cout<<o[i]<<e[i];
      |         ^~~~
      |         std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:8:24: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    8 |   if(o.size()>e.size())cout<<o.back();
      |                        ^~~~
      |                        std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:9:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    9 |   cout<<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:9:9: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    9 |   cout<<endl;
      |         ^~~~
      |         std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~