#!/bin/python3

import sys

def bonAppetit(n, k, b, ar):
    sum=0
    for i in ar:
        sum+=i
    sum-=ar[k]
    sum=sum/2
    if(sum==b):
        return("Bon Appetit")
    else:
        return(int(b-sum))

n, k = input().strip().split(' ')
n, k = [int(n), int(k)]
ar = list(map(int, input().strip().split(' ')))
b = int(input().strip())
result = bonAppetit(n, k, b, ar)
print(result)

