/in/foo.cc: In member function 'void Link_Cut_Tree::splay(int)':
/in/foo.cc:35:30: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
    if(!isroot(y)){if(ch[z][0]==y^ch[y][0]==x)rotate(x);else rotate(y);}
                      ~~~~~~~~^~~