 import java.util.*; 
 
public class Main{  
  public static void main (String [] args){    
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int d[] = new int [N];
    for(int i=0; i<N; i++){
      d[i]=sc.nextInt();
    }
    Arrays.sort(d);
    for(int i=0; i<N; i++){
      System.out.println(d[N/2]-d[N/2-1]);
      break;
    }
  }
}
    
     import java.util.*; util.* java public class Main{  
  public static void main (String [] args){    
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int d[] = new int [N];
    for(int i=0; i<N; i++){
      d[i]=sc.nextInt();
    }
    Arrays.sort(d);
    for(int i=0; i<N; i++){
      System.out.println(d[N/2]-d[N/2-1]);
      break;
    }
  }
} Main public static void main (String [] args){    
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int d[] = new int [N];
    for(int i=0; i<N; i++){
      d[i]=sc.nextInt();
    }
    Arrays.sort(d);
    for(int i=0; i<N; i++){
      System.out.println(d[N/2]-d[N/2-1]);
      break;
    }
  } main {    
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int d[] = new int [N];
    for(int i=0; i<N; i++){
      d[i]=sc.nextInt();
    }
    Arrays.sort(d);
    for(int i=0; i<N; i++){
      System.out.println(d[N/2]-d[N/2-1]);
      break;
    }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int d[] = new int [N]; d new int [N] N for(int i=0; i<N; i++){
      d[i]=sc.nextInt();
    } int i=0; int i=0; i 0 i<N i N i++ i++ i {
      d[i]=sc.nextInt();
    } {
      d[i]=sc.nextInt();
    } d[i]=sc.nextInt() d[i] d i sc.nextInt() sc.nextInt sc Arrays.sort(d) Arrays.sort Arrays d for(int i=0; i<N; i++){
      System.out.println(d[N/2]-d[N/2-1]);
      break;
    } int i=0; int i=0; i 0 i<N i N i++ i++ i {
      System.out.println(d[N/2]-d[N/2-1]);
      break;
    } {
      System.out.println(d[N/2]-d[N/2-1]);
      break;
    } System.out.println(d[N/2]-d[N/2-1]) System.out.println System.out System System.out d[N/2]-d[N/2-1] d[N/2] d N/2 N 2 d[N/2-1] d N/2-1 N/2 N 2 1 break; String [] args args public class Main{  
  public static void main (String [] args){    
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int d[] = new int [N];
    for(int i=0; i<N; i++){
      d[i]=sc.nextInt();
    }
    Arrays.sort(d);
    for(int i=0; i<N; i++){
      System.out.println(d[N/2]-d[N/2-1]);
      break;
    }
  }
} public class Main{  
  public static void main (String [] args){    
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int d[] = new int [N];
    for(int i=0; i<N; i++){
      d[i]=sc.nextInt();
    }
    Arrays.sort(d);
    for(int i=0; i<N; i++){
      System.out.println(d[N/2]-d[N/2-1]);
      break;
    }
  }
} Main
 import java.util.*; 
 
public class Main{  
  public static void main (String [] args){    
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int d[] = new int [N];
    for(int i=0; i<N; i++){
      d[i]=sc.nextInt();
    }
    Arrays.sort(d);
    for(int i=0; i<N; i++){
      System.out.println(d[N/2]-d[N/2-1]);
      break;
    }
  }
}
    
    
