e-olymp
Problems

Cheese for Anfisa - 2

Cheese for Anfisa - 2

When Master cut cheese in the task «Cheese for Anfisa» he had pieces of cheese like a rectangular parallelepiped with different integer lengths of sides. When he was preparing new food from cheese for Anfisa a master had to cut these pieces of cheese on blocks with a side equal 1. What was the master doing least quantity of cuts when he cut these pieces of cheese, if he cut one piece of cheese on two parts each time.

Input

One line contains three numbers a, b, c (1a, b, c2 *109) - the lengths of cheese sides.

Output

Print the required minimum number of cuts if it is known that it is no more than 1018.

Time limit 1 second
Memory limit 128 MiB
Input example #1
2 3 4
Output example #1
23