/in/foo.cc: In function 'bool two(std::__cxx11::string, int)':
/in/foo.cc:15:6: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(i==s.length()-1){
     ~^~~~~~~~~~~~~~
/in/foo.cc: In function 'bool one(std::__cxx11::string, int)':
/in/foo.cc:24:6: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(i==s.length()-1){
     ~^~~~~~~~~~~~~~
/in/foo.cc: In function 'SuanShi huajian(std::__cxx11::string)':
/in/foo.cc:47:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s.length();i++) {   
              ~^~~~~~~~~~~
/in/foo.cc:171:14: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   if(yudeng=0){
              ^
/in/foo.cc:40:6: warning: unused variable 'a' [-Wunused-variable]
  int a=0;
      ^