Competitions

# 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 106.

#### Output

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

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

Output example #1
26