# New FE

Author: mathforces
Problem has been solved: 48 times

Русский язык | English Language

For some function $f: Z \to Z$ it turned out that $f (n) + f (m) = f (n + 1) + f (m-1)$, for any $n$, $m \in Z$. If $f (2021) = 1202$ and $f (1202) = 2021$, then what is the product of the digits of $f (1)$?