/in/foo.cc: In function 'void add(int&, int, int)':
/in/foo.cc:65:10: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   int M=L+R>>1;
         ~^~
/in/foo.cc: In function 'int ask(int, int, int)':
/in/foo.cc:73:9: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int M=L+R>>1;
        ~^~
/in/foo.cc: In function 'void dfs1(int, int)':
/in/foo.cc:90:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0;i<ut[u].size();++i){
          ~^~~~~~~~~~~~~
/in/foo.cc: In function 'void dfs2(int, int)':
/in/foo.cc:103:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0;i<dt[u].size();++i){
          ~^~~~~~~~~~~~~