Тавсифи масъала

Somon has $n$ types of flowers, one of each. He is going to choose one or more of these flowers to make a bouquet. However, she does not like two numbers $a$ and $b$ , so the number of flowers in the bouquet cannot be equal to $a$ or $b$ . How many different bouquets can Somon make? Find the number of bouquets modulo $(10^9+7)$ . Here, two bouquets are considered different if there is a flower that is used in one bouquet but absent in the other.

Input Format

The only line of the input contains three integers $n$ , $a$ and $b$ $(2 \le n \le 10^9, 1 \le a < b \le \min(n, 2 \times 10^5))$ .

Output Format

Print a single number --- the answer to the problem modulo $(10^9+7)$ .

Мисолҳо

Мисол 1

Вуруд

4 1 3

Баромад

Мисол 2