/in/foo.cc: In function 'void rotate(int, int&)':
/in/foo.cc:16:28: warning: statement has no effect [-Wunused-value]
   if (t[z][0] == y)t[z][0] == x;
                    ~~~~~~~~^~~~
/in/foo.cc:17:16: warning: statement has no effect [-Wunused-value]
   else t[z][1] == x;
        ~~~~~~~~^~~~
/in/foo.cc: In function 'void splay(int, int&)':
/in/foo.cc:27:18: warning: unused variable 'z' [-Wunused-variable]
   int y = fa[x], z = fa[y];
                  ^