'use strict';
process.stdin.resume();
process.stdin.setEncoding('utf-8');
let inputString = '';
let currentLine = 0;
process.stdin.on('data', function(inputStdin) {
inputString += inputStdin;
});
process.stdin.on('end', function() {
inputString = inputString.split('\n');
main();
});
function readLine() {
return inputString[currentLine++];
}
/*
* Complete the 'bonAppetit' function below.
*
* The function accepts following parameters:
* 1. INTEGER_ARRAY bill
* 2. INTEGER k
* 3. INTEGER b
*/
function bonAppetit(bill, k, b) {
// Write your code here
let res = 0
for(let i = 0 ; i < bill.length ; i++ ){
if(bill[i] == bill[k]){
continue
}
res += bill[i]
}
res /= 2
if(res==b)
{
console.log("Bon Appetit")
}else if(b>res){
console.log(b - res)
} else{
console.log(res - b)
}
console.log(bill, k, b)
}
function main() {
const firstMultipleInput = readLine().replace(/\s+$/g, '').split(' ');
const n = parseInt(firstMultipleInput[0], 10);
const k = parseInt(firstMultipleInput[1], 10);
const bill = readLine().replace(/\s+$/g, '').split(' ').map(billTemp => parseInt(billTemp, 10));
const b = parseInt(readLine().trim(), 10);
bonAppetit(bill, k, b);
}
