/in/foo.cc: In function 'bool isT(std::__cxx11::string)':
/in/foo.cc:11:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<a.length()/2;i++){
               ^
/in/foo.cc: In function 'bool fanzhuan(std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:21:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<a.length();i++){
               ^
/in/foo.cc:22:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<a.length();j++){
                ^
/in/foo.cc:27:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(j==a.length()-1&&b[j]!=a[i]){
        ^