/in/foo.cc: In member function 'void Segment_tree::build(int, int, int)':
/in/foo.cc:47:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   int mid = l + r>> 1;
             ~~^~~
/in/foo.cc: In member function 'void Segment_tree::modify(int, int, int, int)':
/in/foo.cc:61:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   int mid = l + r>>1;
             ~~^~~