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) {
// Write your code here
int actual=0;

for(int i=0;i<bill.size();i++){
    if(i==k){
        continue;
    }
    actual+=bill.get(i);

}
actual=actual/2;
if(actual==b){
    System.out.println("Bon Appetit");
}
else{
    System.out.println(b-actual);
}

}

}

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();
}

}