In the first sample the original order of tanks is 1, 2, 3. The first tank sends a message to the second one, then the second tank sends it to the third one — it takes two seconds. The third tank moves to the beginning of the column and the order of tanks now is 3, 1, 2. The third tank sends a message to the first one, then the first one sends it to the second one — it takes two more seconds. The second tank moves to the beginning and the order of the tanks is now 2, 3, 1. With this arrangement, the second tank can immediately send a message to the first one, since the message receiving radius of the first tank is large enough — it takes one second. Finally, the tanks return to their original order 1, 2, 3. In total, the exercise takes 5 seconds.
In the second sample, all five tanks are the same and sending a single message takes two seconds, so in total the exercise takes 10 seconds.