foo.cc: In member function 'void tree::build(int, int, int)':
foo.cc:24:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   24 |         int mid = L + R >> 1;
      |                   ~~^~~
foo.cc: In member function 'void tree::modify(int, int, int, int)':
foo.cc:34:27: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   34 |         int mid = nd[p].L + nd[p].R >> 1;
      |                   ~~~~~~~~^~~~~~~~~
foo.cc: In member function 'void tree::query(int, int)':
foo.cc:49:27: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   49 |         int mid = nd[p].L + nd[p].R >> 1;
      |                   ~~~~~~~~^~~~~~~~~
foo.cc: In member function 'void tree::changeTree(int, int)':
foo.cc:67:27: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   67 |         int mid = nd[p].L + nd[p].R >> 1;
      |                   ~~~~~~~~^~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务