foo.cc: In member function 'void Splay::splay(int)':
foo.cc:30:31: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   30 |         for (int f = fa[k]; f = fa[k]; rotate(k)) {
      |                             ~~^~~~~~~
foo.cc: In function 'int main()':
foo.cc:140:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  140 |     scanf("%d %d", &n, &mn);
      |     ~~~~~^~~~~~~~~~~~~~~~~~
foo.cc:144:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  144 |         scanf("\n%c %d", &op, &k);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~

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