/in/foo.cc: In function 'std::__cxx11::string work(std::__cxx11::string)':
/in/foo.cc:15:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<s[i].length();j++) {
               ~^~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:36:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(i<str.length()-1) {
        ~^~~~~~~~~~~~~~~
/in/foo.cc:39:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while(i<str.length()-1&&str[i]==' ') i++;
          ~^~~~~~~~~~~~~~~
/in/foo.cc:42:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(i<str.length()-1&&str[i]==' ') i++;
         ~^~~~~~~~~~~~~~~
/in/foo.cc:44:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(i<str.length()-1&&str[i]!=' '&&str[i]!='!') {
         ~^~~~~~~~~~~~~~~
/in/foo.cc:52:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<res.size()-1;i++) cout<<res[i]<<" ";
              ~^~~~~~~~~~~~~