Language: C++

#include<bits/stdc++.h>


int main() {
    int op;
    string start = "";
    cin>>start>>endl;
    cin>>op>>endl;
    string t = "";
    while(op) {
       cin>>t>>endl;
       if(t[0] == '2') {
            
            if(t[2] == '2) {
               start += t[4];
             }
             else {
               string s = "";
               s += t[4];
               s+= start;
               start = s;
             }
         
       }else {
          reverse(start.begin(), start.end()); 
       }
      
    op--;  
    }
  
      
    return 0; 
}

Compiler output:
a.cc:14:24: warning: missing terminating ' character
   14 |             if(t[2] == '2) {
      |                        ^
a.cc:14:24: error: missing terminating ' character
   14 |             if(t[2] == '2) {
      |                        ^~~~~
a.cc: In function 'int main()':
a.cc:6:5: error: 'string' was not declared in this scope
    6 |     string start = "";
      |     ^~~~~~
a.cc:6:5: 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,
                 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:7:5: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    7 |     cin>>start>>endl;
      |     ^~~
      |     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:7:10: error: 'start' was not declared in this scope
    7 |     cin>>start>>endl;
      |          ^~~~~
a.cc:7:17: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    7 |     cin>>start>>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:9:11: error: expected ';' before 't'
    9 |     string t = "";
      |           ^~
      |           ;
a.cc:11:13: error: 't' was not declared in this scope; did you mean 'tm'?
   11 |        cin>>t>>endl;
      |             ^
      |             tm
a.cc:16:14: error: expected primary-expression before '}' token
   16 |              }
      |              ^
a.cc:15:30: error: expected ')' before '}' token
   15 |                start += t[4];
      |                              ^
      |                              )
   16 |              }
      |              ~                
a.cc:14:15: note: to match this '('
   14 |             if(t[2] == '2) {
      |               ^
a.cc:16:14: error: expected primary-expression before '}' token
   16 |              }
      |              ^
a.cc:18:22: error: expected ';' before 's'
   18 |                string s = "";
      |                      ^~
      |                      ;
a.cc:19:16: error: 's' was not declared in this scope
   19 |                s += t[4];
      |                ^
a.cc:24:9: error: 'else' without a previous 'if'
   24 |        }else {
      |         ^~~~
a.cc:25:11: error: 'reverse' was not declared in this scope; did you mean 'std::reverse'?
   25 |           reverse(start.begin(), start.end());
      |           ^~~~~~~
      |           std::reverse
In file included from /usr/include/c++/14/algorithm:86,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/pstl/glue_algorithm_defs.h:249:1: note: 'std::reverse' declared here
  249 | reverse(_ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __last);
      | ^~~~~~~
a.cc: At global scope:
a.cc:32:5: error: expected unqualified-id before 'return'
   32 |     return 0;
      |     ^~~~~~
a.cc:33:1: error: expected declaration before '}' token
   33 | }
      | ^