foo.cc: In function ‘void build(int, int, int)’:
foo.cc:33:18: warning: suggest parentheses around ‘+’ inside ‘>>’ [-Wparentheses]
   33 |         int mid=l+r>>1;
      |                 ~^~
foo.cc: In function ‘tree query(int, int, int)’:
foo.cc:43:23: warning: suggest parentheses around ‘+’ inside ‘>>’ [-Wparentheses]
   43 |         int mid=t[u].l+t[u].r>>1;
      |                 ~~~~~~^~~~~~~
foo.cc: In function ‘void update(int, int, int)’:
foo.cc:69:23: warning: suggest parentheses around ‘+’ inside ‘>>’ [-Wparentheses]
   69 |         int mid=t[u].l+t[u].r>>1;
      |                 ~~~~~~^~~~~~~