Lunch

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

Input

Three non-negative integers $a,b$ and $c$ are given. All integers do not exceed $10^6$.

Output

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

Examples