Electrical outlets

http://electricaloutlet.org/

Sweden uses plug type C or F.
Italy uses plugs type C or F or the old L plug, which is similar to C, but with 3 prongs.
F is the Schuko plug (German invention) and won’t fit in the C or L socket because the prongs are fatter.
If the outlet in your hotel has type C or L, and your appliance uses a shuko, they will probably be able to provide you with an adapter for F. Every Italian has plenty of adapters to plug an F, because F is now becoming very common in Italy..

Roberto, every Italian has plenty of Schuko adapters but when you need them they always seem to be missing :-)

I know what you say lachera.
When you need it, you can never find it in the junk drawer. But you can find all others, including the two different types of L (10A and 16A) that were the norm in the 1960s.

I think the OP means the straightener has a two prong, 6 sided plug, kind of a "flattened hexagon" (a true hexagon has 6 equal sides with 120° angles). It sound like a type C plug (not a type F Schuko plug). Type C (note the 6 sided, flattened hexagon shape) has Ø4.0 mm pins and should fit in either type F or L receptacles (sockets).

If the outlet in your hotel has type C

Type C receptacles are rare today (only where "grandfathered in"). Most codes don't allow them for new construction because they are not grounded.

This website shows the configuration of plugs and receptacles and in what countries they are used.

Type C: http://www.iec.ch/worldplugs/typeD.htm (Two prong ungrounded)

Type F: http://www.iec.ch/worldplugs/typeF.htm (Two prong with flat ground contacts in the sides)

Type L: http://www.iec.ch/worldplugs/typeL.htm (Three pin grounded)