Problems

# Paint3D

# Paint3D

Figures on a sheet of photo editor **PAІNT** can select and copy (in full), paste and move (drag). What is the smallest number of such operations should be used to having an image on a sheet of the unit cube, to build another image - a cuboid with dimensions `A`

x`B`

x`C`

made up of these cubes?

#### Input

In the input file contains the number of `A`

, `B`

, `C`

. `1 ≤ A, B, C ≤ 100`

.

#### Output

The output file to write the answer - the smallest number of operations.

Input example #1

2 3 4

Output example #1

20