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DFA, lower bound on number of states, language with primes and remainders

Let $p \ge 5$ be a prime number and $L_p$ be a language of words over $\{0,1\}$ that read in binary from right (i.e. from least significant bit) give a number that gives remainder modulo $p$ from the set $\{1,2, \ldots, \frac{p-1}{2}\}$.

How to show that:

Every DFA recognizing $L_p$ has at least $2p$ states.