You Do Need power plug adapter while traveling from San Marino to Benin.

Here is Why You Need An Adapter

The outlet and plug type used in Benin are C and E and in San Marino are C, F and L. This is how they look like.

San Marino

In San Marino, outlets of type C, F and L are in use.

Type C

Type F

Type L

Benin

In Benin, outlets of type C and E are in use.

Type C

Type E