Divide the Problems

Takahashi made N problems for competitive programming. The problems are numbered 1 to N, and the difficulty of Problem i is represented as an integer d_i (the higher, the harder).

He is dividing the problems into two categories by choosing an integer K, as follows:

• A problem with difficulty K or higher will be for ARCs.
• A problem with difficulty lower than K will be for ABCs.

How many choices of the integer K make the number of problems for ARCs and the number of problems for ABCs the same?

• 2 \leq N \leq 10^5
• N is an even number.
• 1 \leq d_i \leq 10^5
• All values in input are integers.

Input

Input is given from Standard Input in the following format:

N d_1 d_2 ... d_N

Output

Print the number of choices of the integer K that make the number of problems for ARCs and the number of problems for ABCs the same.

Examples

Input

6 9 1 4 4 6 7

Output

2

Input

8 9 1 14 5 5 4 4 14

Output

0

Input

14 99592 10342 29105 78532 83018 11639 92015 77204 30914 21912 34519 80835 100000 1

Output

42685

inputFormat

input are integers.

Input

Input is given from Standard Input in the following format:

N d_1 d_2 ... d_N

outputFormat

Output

Print the number of choices of the integer K that make the number of problems for ARCs and the number of problems for ABCs the same.

Examples

Input

6 9 1 4 4 6 7

Output

2

Input

8 9 1 14 5 5 4 4 14

Output

0

Input

14 99592 10342 29105 78532 83018 11639 92015 77204 30914 21912 34519 80835 100000 1

Output

42685

样例

8
9 1 14 5 5 4 4 14

0