Suppose F$\_($k $)$is a PRF and it outputs n bits. We define a symmetric key encryption algorithm as follows:

The plaintext m is with length $2$n$,$ when encrypting m$,$ the algorithm chooses a random r$,$ computes F$\_($k $)($r$)$ and obtains y$.$

The algorithm then computes $($y$||$y$)$m $($where $$ stands for the XOR operation$),$ i$.$e$.,$ using y to mask both the first half and second half of the message.

Is such encryption algorithm IND$-$CPA secure$?$ Briefly explain.