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