/in/foo.cc: In function 'long long int work(std::__cxx11::string)':
/in/foo.cc:38:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<s.size();i++)  
                 ~^~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:151:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<sss.size();i++)  
                 ~^~~~~~~~~~~
/in/foo.cc:154:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<ss.size();i++)  
                 ~^~~~~~~~~~
/in/foo.cc:161:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=0;j<s2.size();j++)  
                     ~^~~~~~~~~~
/in/foo.cc:163:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=0;j<s.size();j++)  
                     ~^~~~~~~~~
/in/foo.cc: In function 'int pre(char)':
/in/foo.cc:31:1: warning: control reaches end of non-void function [-Wreturn-type]
 }  
 ^