import java.util.*; import java.io.*; import java.math.*; import java.util.stream.Stream; public class Main{ /* 入出力 */ static BufferedReader buff = new BufferedReader(new InputStreamReader(System.in)); static StringTokenizer st; static PrintWriter output = new PrintWriter(System.out); static Scanner sc = new Scanner(System.in); /* 定数 */ static final int [] y4 = {0,1,0,-1}; static final int [] x4 = {1,0,-1,0}; static final int INF1 = Integer.MAX_VALUE; static final long INF2 = Long.MAX_VALUE; static final long MOD1 = (long)1e9+7; static final long MOD2 = 998244353; /* Main */ public static void main(String[] args) throws IOException{ int n = sc.nextInt(); int [] A = new int[2*n]; for(int i=0;i<2*n;i++) A[i] = sc.nextInt(); Arrays.sort(A); long ans = 0; for(int i=0;i