Competitions

# Задачі для початківців

# 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** (**1** ≤ **a**, **b**, **c** ≤ **2** *`10`

) - the lengths of cheese sides.^{9}

#### Output

Print the required minimum number of cuts if it is known that it is no more than `10`

.^{18}

Input example #1

2 3 4

Output example #1

23