Cossack Vus and the Secret Letter

Cossack Vus urgently needs to send a letter containing secret information to his comrades. He visits a store that has $a$ envelopes, $b$ stamps with embroidery, and $c$ stamps with trousers.

To mail the letter, Cossack Vus must purchase:

• one envelope

• one or two stamps

Cossack Vus dislikes monotony, so he will buy at most one stamp of each type.

How many different ways can Cossack Vus make his purchase?

Two purchase methods are considered different if there is at least one envelope or stamp that Cossack Vus buys in one method but not in the other.

Giriş verilənləri

The first line contains three integers $a$, $b$, and $c$ $(1\le a,b,c\le 500)$ — representing the number of envelopes, stamps with embroidery, and stamps with trousers, respectively.

Çıxış verilənləri

Output a single number — the number of ways to purchase the envelope and stamps.

Nümunələr

Qeyd

In the first example, Cossack Vus can purchase:

• an envelope and a stamp with embroidery

• an envelope and a stamp with trousers

• an envelope and both stamps

In the second example, Cossack Vus can purchase:

• an envelope and a stamp with trousers (1 way)

• an envelope and one of the two stamps with embroidery (2 ways)

• an envelope, a stamp with trousers, and one of the two stamps with embroidery (2 ways)