/in/foo.cc: In function 'void helper_normal(std::vector<int>&, std::pair<int, int>&, int)':
/in/foo.cc:41:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     } else if (idx == nums.size() - 1) {
                ~~~~^~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'std::__cxx11::string get_conn(std::__cxx11::string)':
/in/foo.cc:61:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<res.size();i++) {
                 ~^~~~~~~~~~~
/in/foo.cc:64:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         } else if(i==res.size()-1) {
                   ~^~~~~~~~~~~~~~
/in/foo.cc: In function 'std::__cxx11::string get_normal(std::__cxx11::string)':
/in/foo.cc:77:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=1;i<s.size();i++) {
                 ~^~~~~~~~~