Competitions

# Комбинаторика. Формула

# Lunch

Vlad wants to take for lunch a couple of fruits. He has **a** different bananas, **b** different apples and **c** different pears. In how many ways can he choose **2** different fruits from available?

#### Input

Three non-negative integers are given: **a**, **b** and **c**. All integers do not exceed `10`

.^{6}

#### Output

Print the number of ways to choose **2** different fruits for a lunch.

Input example #1

3 4 2

Output example #1

26