foo.cc:8:26: error: conflicting declaration 'std::unordered_map<char, int> cs'
 unordered_map<char, int> cs =
                          ^~
foo.cc:7:8: note: previous declaration as 'std::__cxx11::string cs'
 string cs="0123456789ABCDEF";
        ^~
foo.cc:14:12: error: 'stirng' was not declared in this scope
 string add(stirng& a,string& b,int n)
            ^~~~~~
foo.cc:14:12: note: suggested alternative: 'stdin'
 string add(stirng& a,string& b,int n)
            ^~~~~~
            stdin
foo.cc:14:20: error: 'a' was not declared in this scope
 string add(stirng& a,string& b,int n)
                    ^
foo.cc:14:28: error: expected primary-expression before '&' token
 string add(stirng& a,string& b,int n)
                            ^
foo.cc:14:30: error: 'b' was not declared in this scope
 string add(stirng& a,string& b,int n)
                              ^
foo.cc:14:32: error: expected primary-expression before 'int'
 string add(stirng& a,string& b,int n)
                                ^~~
foo.cc:15:1: error: expected ',' or ';' before '{' token
 {
 ^
foo.cc: In function 'int main()':
foo.cc:57:4: error: return-statement with no value, in function returning 'int' [-fpermissive]
    return ;
    ^~~~~~
foo.cc:59:67: error: no match for call to '(std::__cxx11::string {aka std::__cxx11::basic_string<char>}) (std::__cxx11::string&, std::__cxx11::string&, int&)'
   string temp(m); reverse(temp.begin(),temp.end()); m=add(m,temp,n);//加
                                                                   ^