bill-division

#!/bin/python3

import math
import os
import random
import re
import sys

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

def bonAppetit(bill, k, b):
    listaAna = []
    contador = 0
    totalAna = 0
    
    while contador < len(bill):
        if contador != k:
            listaAna.append(bill[contador])
        contador += 1
    
    totalAna = int(sum(listaAna)/2)
    
    if totalAna == b:
        print('Bon Appetit')
    else:
        print(b - totalAna)

if __name__ == '__main__':
    first_multiple_input = input().rstrip().split()

    n = int(first_multiple_input[0])

    k = int(first_multiple_input[1])

    bill = list(map(int, input().rstrip().split()))

    b = int(input().strip())

    bonAppetit(bill, k, b)