Select all the incorrect statement about IPC.

$V$ operation always increases the count of semaphore by $1.$

FIFO is a bidirectional communication method between processes.

Pipe can be accessed by any process.

Shared memory is the most efficient inter$-$process communication methad.

P operation aiways reduce the count of semaphore by $1.$

Messages in a message queue can only be read in a FIFO manner.