ScicomLoveBug

The original title of this problem was ScicomLove. However, because of lovebugs, the angry problem setter changed the title to ScicomLoveBug!

There are currently $N$ lovebugs in the club room. While summer continues, the number of lovebugs increases by $A$ every day.

Find the expected number of lovebugs in the club room after $D$ days.

The input is given in the following format.

$N\ A\ D$

Print the expected number of lovebugs in the club room after $D$ days.

• $1 \leq N \leq 10^9$.
• $1 \leq A \leq 10^9$.
• $1 \leq D \leq 10^9$.