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: Wrong Answer)

#include<stdio.h>
int main(){
  int i, n, j, temp, x=0, y=0, ans=0;
  scanf("%d", &n);
  int a[n];
  for(i=0;i<n;i++){
    scanf("%d", &a[i]);
  }
  for(i=0; i<n; i++){
    for(j=n-1; j>i; j--){
      if(a[j] < a[j-1]){
        temp = a[j];
        a[j] = a[j-1];
        a[j-1] = temp;
      }
    }
  }
  for(i=0;i<a[0];i++){
    for(j=0;j<n;j++){
      if(a[j]>=i){
        x++;
      }else{
        y++;
      }
    }
    if(x==y){
      ans++;
    }
    x=0;
    y=0;
  }
  printf("%d\n", ans);
  return 0;
}