'Using 2 flags of 2 colors each, the U.S. Navy sends short-range messages by this system'
semaphore
2: Using 2 flags of 2 colors each, the U.S. Navy sends short-range messages by this system
Using 2 flags of 2 colors each, the U.S. Navy sends short-range messages by this system
Using 2 flags of 2 colors each, the U.S. Navy sends short-range messages by this system
2
semaphore
2