import java.util.Scanner; import static java.lang.System.*; public class Main { public static void main(String[] args) { Scanner scan = new Scanner(in); double n = scan.nextDouble(); double k = scan.nextDouble(); double r = 0; for (double i = 0; i < n; ++i) { double c = scan.nextDouble(); if (i == k) continue; r += c; } double p = scan.nextDouble(); r = p - r / 2; if (r == 0) { out.println("Bon Appétit"); } else { out.println(r); } } }