/in/foo.cc: In constructor 'segnode::segnode(int, int)':
/in/foo.cc:42:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
             int mid = l + r >> 1;
                       ~~^~~
/in/foo.cc: In member function 'matrix segnode::query(int, int)':
/in/foo.cc:61:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
         int mid = l + r >> 1;
                   ~~^~~