Language: C++

#include<bits/stdc++.h>
usingnamespacestd;
intmain() {
  string s,t;
  cin>>s>>t;
  intans= 0;
  if(s[0] ==t[0])ans++;
  if(s[1] ==t[1])ans++;
  if(s[2] ==t[2])ans++;
  cout<<ans<<endl;
  return0;
}

Compiler output:
a.cc:2:1: error: 'usingnamespacestd' does not name a type
    2 | usingnamespacestd;
      | ^~~~~~~~~~~~~~~~~
a.cc:3:1: error: ISO C++ forbids declaration of 'intmain' with no type [-fpermissive]
    3 | intmain() {
      | ^~~~~~~
a.cc: In function 'int intmain()':
a.cc:4:3: error: 'string' was not declared in this scope
    4 |   string s,t;
      |   ^~~~~~
a.cc:4:3: 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,
                 from a.cc:1:
/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:5:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    5 |   cin>>s>>t;
      |   ^~~
      |   std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:5:8: error: 's' was not declared in this scope
    5 |   cin>>s>>t;
      |        ^
a.cc:5:11: error: 't' was not declared in this scope; did you mean 'tm'?
    5 |   cin>>s>>t;
      |           ^
      |           tm
a.cc:6:3: error: 'intans' was not declared in this scope
    6 |   intans= 0;
      |   ^~~~~~
a.cc:7:18: error: 'ans' was not declared in this scope; did you mean 'abs'?
    7 |   if(s[0] ==t[0])ans++;
      |                  ^~~
      |                  abs
a.cc:8:18: error: 'ans' was not declared in this scope; did you mean 'abs'?
    8 |   if(s[1] ==t[1])ans++;
      |                  ^~~
      |                  abs
a.cc:9:18: error: 'ans' was not declared in this scope; did you mean 'abs'?
    9 |   if(s[2] ==t[2])ans++;
      |                  ^~~
      |                  abs
a.cc:10:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   10 |   cout<<ans<<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:10:9: error: 'ans' was not declared in this scope; did you mean 'abs'?
   10 |   cout<<ans<<endl;
      |         ^~~
      |         abs
a.cc:10:14: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   10 |   cout<<ans<<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)
      |     ^~~~
a.cc:11:3: error: 'return0' was not declared in this scope
   11 |   return0;
      |   ^~~~~~~
a.cc:12:1: warning: no return statement in function returning non-void [-Wreturn-type]
   12 | }
      | ^