/in/foo.cc: In function 'void built_tree(int, int, int)':
/in/foo.cc:19:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=l+r>>1;
          ~^~
/in/foo.cc: In function 'void change(int, int, double, int, int)':
/in/foo.cc:31:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=l+r>>1;
          ~^~