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: Time Limit Exceeded)

#include <stdio.h>

void sort(int A[], int len_A){
    int i, j, tmp;
    for (i = 0; i < len_A - 1; i++){
        for (j = 0; j < len_A - 1; j++){
            if (A[j + 1] < A[j]){
                tmp = A[j];
                A[j] = A[j + 1];
                A[j + 1] = tmp;
            }
        }
    }
}


int main(void){
    int n;
    scanf("%d", &n);
    int d[n];
    for (int i = 0; i < n; i++){
        scanf("%d", &d[i]);
    }

    sort(d, n);
    int tmp = (n - 1) / 2;
    int ans = d[tmp + 1] - d[tmp];
    printf("%d\n", ans);

    return 0;
}