Problem:
Score : 300 points

Problem Statement

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?

Problem Statement

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.

Sample Input 1

6
9 1 4 4 6 7

Sample Output 1

2

If we choose K=5 or 6, Problem 1, 5, and 6 will be for ARCs, Problem 2, 3, and 4 will be for ABCs, and the objective is achieved.
Thus, the answer is 2.

Sample Input 2

8
9 1 14 5 5 4 4 14

Sample Output 2

0

There may be no choice of the integer K that make the number of problems for ARCs and the number of problems for ABCs the same.

Sample Input 3

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

Sample Output 3

42685

Solution in C (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
int compare(const void *a, const void *b)
{
    int da = *( int*)a;
    int db = *(int*)b;
    int val = 0;
    if(da > db) {
        val = -1;
    } else if (da == db) {
        val = 0;
    } else {
        val = 1;
    }

    return val;
}

int main()
{
    int n,i;
    scanf("%d",&n);
    int a[30];
    for(i=0;i<n;i++){
        scanf("%d",&a[i]);
    }
    qsort(a,n,sizeof(a[0]),compare);
    printf("\n%d",a[(n/2)-1]-a[(n/2)]);
}