Chocolate lover#9002
Aziz is very fond of eating chocolate. But since chocolate is very bad for teeth, his father won't let him eat a lot of chocolate. This time he managed to convince his father and get permission to eat one chocolate every day. Aziz loves two types of chocolate. One weighs grams, the other grams. Aziz's father allowed him to eat one chocolate every day for days, but with condition that he should not eat the same chocolate for two days in a row. Now Aziz is worried about only one question. How to make sure that within days he could eat the maximum amount (in grams) of chocolate.
Help him with this.
One line contains three integers and b~(1 \le n, a, b \le 10^9).
Print the maximum amount of chocolate (in grams) that Aziz can consume during days.
Example 1
Example 2