/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:40:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while(i<str.length()-1&&str[i]==' ') i++;
          ~^~~~~~~~~~~~~~~
/in/foo.cc:43:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(i<str.length()-1&&str[i]==' ') i++;
         ~^~~~~~~~~~~~~~~
/in/foo.cc:45:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(i<str.length()-1&&str[i]!=' '&&str[i]!='!') {
         ~^~~~~~~~~~~~~~~