My Java 8 Solution:

`public static void bonAppetit(List bill, int k, int b) { int actual, charged = b, sum = 0;

    for(int i = 0; i<bill.size(); i++) {
        if(i != k) {
            sum += bill.get(i);
        }
    }
    actual = sum/2;
    if (actual == charged) {
        System.out.println("Bon Appetit");
    } else {
        System.out.println(charged - actual);
    }

    }