PUZZLE 139 Hankie Stamp

Here we have five handkerchiefs.
They are all the exact same shape, colour and size.
Using a round stamp, you need to mark the handkerchiefs so that they can all be told apart.
What is the fewest number of times you need to use the stamp?

Hint 1

Just because there are five hand-kerchiefs, it doesn't mean you have to use the stamp five times.

Hint 2

The shape of the stamp and the location that is stamped would enable you to tell the difference between the handkerchiefs.

Hint 3

The handkerchiefs don't have to be stamped with a circle.

Super Hint

How about lining up several handkerchiefs and stamping them in one go?

Answer for 'Hankie Stamp'

The answer is '1'.