# From Europe with love

Algebra Level 4

$\large \dfrac{1}{a^4+1}+\dfrac{1}{b^4+1}+\dfrac{1}{c^4+1}+\dfrac{1}{d^4+1}=1$

Let $a,b,c$ and $d$ be positive reals satisfying the equation above, find the minimum value of $20abcd$.

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