import java.util.*; import java.io.*; import java.awt.geom.*; import java.math.*; public class No0275 { static final Scanner in = new Scanner(System.in); static final PrintWriter out = new PrintWriter(System.out,false); static void solve() { int n = in.nextInt(); int[] a = new int[n]; for (int i=0; i<n; i++) { a[i] = in.nextInt(); } Arrays.sort(a); out.printf("%3f\n",(n%2 == 0 ? (double)(a[n/2]+a[n/2-1])/2 : a[n/2])); } public static void main(String[] args) { long start = System.currentTimeMillis(); solve(); out.flush(); long end = System.currentTimeMillis(); //trace(end-start + "ms"); in.close(); out.close(); } static void trace(Object... o) { System.out.println(Arrays.deepToString(o));} }