/in/foo.cc: In function 'void push_down(int)':
/in/foo.cc:68:41: warning: operation on 'st[r].node::maxl' may be undefined [-Wsequence-point]
    st[l].maxl = st[r].maxr = st[r].maxl = st[r].maxl = 0,
                              ~~~~~~~~~~~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'void splay(int, int&)':
/in/foo.cc:146:21: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
    if (st[z].son[1] == y ^ st[y].son[1] == x)
        ~~~~~~~~~~~~~^~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:280:8: warning: variable 'kkkkk' set but not used [-Wunused-but-set-variable]
    int kkkkk;
        ^~~~~