code13

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.function.*;
import java.util.regex.*;
import java.util.stream.*;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;

class Result {

    /*
     * Complete the 'bonAppetit' function below.
     *
     * The function accepts following parameters:
     *  1. INTEGER_ARRAY bill
     *  2. INTEGER k
     *  3. INTEGER b
     */

    public static void bonAppetit(List<Integer> bill, int k, int b) {
        int sum=0;
      for(int i=0;i<bill.size();i++)
    {
        if(i==k)
        {
            continue;
        }
        sum+=bill.get(i);
    }
    int a=sum/2;
    if(a==b){
        System.out.println("Bon Appetit");
    }
    else{
        int diff=b-a;
        System.out.println(diff);
    }
    
        
    }
    
    }



public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

        String[] firstMultipleInput = bufferedReader.readLine().replaceAll("\\s+$", "").split(" ");

        int n = Integer.parseInt(firstMultipleInput[0]);

        int k = Integer.parseInt(firstMultipleInput[1]);

        List<Integer> bill = Stream.of(bufferedReader.readLine().replaceAll("\\s+$", "").split(" "))
            .map(Integer::parseInt)
            .collect(toList());

        int b = Integer.parseInt(bufferedReader.readLine().trim());

        Result.bonAppetit(bill, k, b);

        bufferedReader.close();
    }
}