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++14 (GCC 5.4.1) (judge verdict: Accepted)

/**
*    Name: Ajay
*    Institute: IIITH 
*/

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <deque>
#include <vector>
#include <cstdlib>
#include <iomanip>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <ctime>
#include <string.h>
#define loop(i,a,b) for(int i=a;i<b;i++)
#define loope(i,a,b) for(int i=a;i<=b;i++)
#define LL long long
#define inf 0x7fffffff
#define mod 1000000007
#define pb push_back
#define ppi pair<int,int>
#define vi vector<int>
#define vii vector<ppi>
#define vll vector<LL>
#define mp make_pair
#define fi first
#define se second
using namespace std;

void fastio()
{
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
}
void input()
{
  #ifndef ONLINE_JUDGE
  freopen("input.txt","r",stdin);
  freopen("output.txt","w",stdout);
  #endif
}

int main()
{      
   int n;
  cin>>n;
  int a[n];
  for(int i=0;i<n;i++)
  {
    cin>>a[i];
  }
  if(n&1)
  {
    cout<<0;
    return 0;
  }
  sort(a,a+n);
  int med=(n/2);
  int left=med-1;
  int right=med;
  if(a[left]==a[right])
  {
    cout<<"0";
    return 0;
  }
  cout<<a[right]-a[left];
  return 0;
}