#25 Paint3D

prb25    Figures on a sheet of photo editor PAČNT 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 AxBxC made up of these cubes?

Specifications

   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.

Time Limit: 1 seconds
Balls for the passed test: 10
Complexity: 45%

Example

Example input

2 3 4

Example output

20


Problem URL: http://www.e-olimp.com.ua/en/problems/25