/in/foo.cc: In function 'void build(int, int, int)':
/in/foo.cc:22:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=l+r>>1;
          ~^~
/in/foo.cc: In function 'tree query(int, int, int)':
/in/foo.cc:32:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=l(k)+r(k)>>1;
              ^
/in/foo.cc: In function 'void change(int, int, int)':
/in/foo.cc:42:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=l(k)+r(k)>>1;
              ^