local n;

infix "===" at "==" (v1, v2) {
  local s1, s2, i;
  
  s1 := v1.string;
  s2 := v2.string;

  if s1.length == s2.length
  then
    for i := 0, i < s1.length, i := i + 1
    do
      if s1[i] != s2[i] then return 0 fi  
    od;
     1
  else 0
  fi
}

infix "?" before "+" (v, l) {
  case l of
   {}      ->  0
  | h : tl -> if h === v then 1 else (v ? tl) fi
  esac
}

infix "+++" at "+" (l1, l2) {
  case l1 of
    {}     -> l2
  | h : tl -> (h : tl +++ l2)
  esac
}

n := read ();

write ({1, 2, 3} === {1, 2, 3}); 
write ({1, 2, 3} === {1, 2, 4});
write (1+2 ? {1, 2, 3});
write (1*3+2 ? {1, 2, 3});
write (1*3+2 ? {1, 2, 5});
write (8*4 ? {1, 2, 3} +++ {5, 7, 32, 6})