Niloy's two friends Sanjay and Fahim. Sanjay gives email to Niloy for $8$ days in a row and Fahim gives email to Niloy for $4$ days in a row. So how many days are there in $2020$ when Niloy receives emails from both of them?
(Niloy received emails from Sanjay and Fahim on December $31, 2019$)