/in/foo.cc: In member function 'void node::split(int, node*&, node*&)':
/in/foo.cc:30:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(k <= l->c) {
      ~~^~~~~~~
/in/foo.cc: In member function 'void node::print()':
/in/foo.cc:48:65: warning: format '%d' expects argument of type 'int', but argument 2 has type 'long int' [-Wformat=]
   printf("id=%d %c v=%d c=%d sum=%d\n",this-null,v+'a'-1,v,c,sum);
                                                                 ^