/in/foo.cc: In function 'bool check(std::__cxx11::string)':
/in/foo.cc:22:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i+1<L.size();i+=2)
              ~~~^~~~~~~~~
/in/foo.cc:27:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i+1<L.size();i+=2)
              ~~~^~~~~~~~~
/in/foo.cc:34:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<L.size();i+=2) L2.push_back(L[i]);
               ~^~~~~~~~~
/in/foo.cc:43:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=1;i<L.size();i+=2) L2.push_back(L[i]);
               ~^~~~~~~~~
/in/foo.cc: In function 'LL solve(std::__cxx11::string, LL)':
/in/foo.cc:67:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i+1<L.size();i+=2)
              ~~~^~~~~~~~~
/in/foo.cc:72:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i+1<L.size();i+=2)
              ~~~^~~~~~~~~
/in/foo.cc:85:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int i=0;i<L.size();i+=2) L2.push_back(L[i]);
                ~^~~~~~~~~
/in/foo.cc:92:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int i=1;i<L.size();i+=2) L2.push_back(L[i]);
                ~^~~~~~~~~