CF169A Chores

Petya and Vasya are brothers. Today is a special day for them as their parents left them home alone and commissioned them to do $ n $ chores. Each chore is characterized by a single parameter — its complexity. The complexity of the $ i $ -th chore equals $ h_{i} $ . As Petya is older, he wants to take the chores with complexity larger than some value $ x $ ( $ h_{i}>x $ ) to leave to Vasya the chores with complexity less than or equal to $ x $ ( $ h_{i}

The first input line contains three integers $ n,a $ and $ b $ ( $ 2

Print the required number of ways to choose an integer value of $ x $ . If there are no such ways, print 0.

In the first sample the possible values of $ x $ are 3, 4 or 5. In the second sample it is impossible to find such $ x $ , that Petya got 3 chores and Vasya got 4.