To every pair of numbers $x, y$ the Rule assigns a number $x ∗ y$. Find $1993 ∗ 1935$ if it is known that
$x ∗ x = 0,$ and $x ∗ (y ∗ z) = (x ∗ y) + z$ for any $x, y, z.$

Let's think step by step and output the final answer within \boxed{}.
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