Generally speaking, the process of knocking at the door is ignored.

In other words, the time to ring the bell is zero.

So there are pictures.

| - | - | - | - | - |-

The first "-"is a duration of two seconds. The second "-"is the interval time.

Because there was no interval between the last shots.

So there is (32-2)/5=6.

That is, the interval is 6-2=4.

So under 12, there is 1 1 times 6+2=68 seconds.