In file included from /usr/include/c++/6/backward/hash_map:60:0,
                 from /in/foo.cc:16:
/usr/include/c++/6/backward/backward_warning.h:32:2: warning: #warning This file includes at least one deprecated or antiquated header which may be removed without further notice at a future date. Please use a non-deprecated interface with equivalent functionality instead. For a listing of replacement headers and interfaces, consult the file backward_warning.h. To disable this warning use -Wno-deprecated. [-Wcpp]
 #warning \
  ^~~~~~~
/in/foo.cc: In function 'bool check(std::__cxx11::string)':
/in/foo.cc:25:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<ls.size();i++)
              ~^~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:48:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<ls.size();i++)
              ~^~~~~~~~~~
/in/foo.cc:51:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<s.length();j++)
               ~^~~~~~~~~~~
/in/foo.cc:53:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int k=j+1;k<s.length();k++)
                  ~^~~~~~~~~~~
/in/foo.cc:79:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int j=0;j<s.length();j++)
                ~^~~~~~~~~~~
/in/foo.cc:92:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     else if(j==s.length()-1)
             ~^~~~~~~~~~~~~~
/in/foo.cc:113:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      for(int k=0;k<s.length();k++)
                  ~^~~~~~~~~~~
/in/foo.cc:128:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(mabit>s.size()&&s.size()>=2)
      ~~~~~^~~~~~~~~
/in/foo.cc:130:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int j = 0;j<s.length()-1;j++)
                  ~^~~~~~~~~~~~~
/in/foo.cc:135:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      for(int k=0;k<s.length();k++)
                  ~^~~~~~~~~~~
/in/foo.cc:157:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int k=0;k<s.length();k++)
                 ~^~~~~~~~~~~
/in/foo.cc:175:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int k=0;k<s.length();k++)
                 ~^~~~~~~~~~~
/in/foo.cc:178:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      if(k==s.length()-1)
         ~^~~~~~~~~~~~~~