/in/foo.cc: In function 'void search(int)':
/in/foo.cc:41:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0;i<tree[now].son.size();i++)
          ~^~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:44:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(j=0;j<tree[s].son.size();j++)
           ~^~~~~~~~~~~~~~~~~~~
/in/foo.cc:52:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0;i<tree[now].son.size();i++)
          ~^~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:59:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0;i<tree[now].son.size();i++)
          ~^~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:40:15: warning: unused variable 's2' [-Wunused-variable]
  int i,j,s,ss,s2;
               ^~