/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:98:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0; i<s.length(); i++) {
               ~^~~~~~~~~~~
/in/foo.cc:146:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  if(yudeng=0) {
             ^
/in/foo.cc:91:6: warning: unused variable 'a' [-Wunused-variable]
  int a=0;
      ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:167:10: warning: unused variable 'item' [-Wunused-variable]
  for(int item: m.two) {
          ^~~~
/in/foo.cc:171:10: warning: unused variable 'item' [-Wunused-variable]
  for(int item: m.one) {
          ^~~~
/in/foo.cc:175:10: warning: unused variable 'item' [-Wunused-variable]
  for(int item: m.zero) {
          ^~~~