public static void main(String[] args) throws IOException {
Scanner scanner = new Scanner(new BufferedInputStream(System.in));
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int n = 1;
while (scanner.hasNextInt()) {
int a = scanner.nextInt();
int b = scanner.nextInt();
if (a == 0) break;
BigInteger sum = BigInteger.ZERO;
BigInteger bb = BigInteger.valueOf(b);
for (int i = 0; i < a; i++) sum = sum.add(scanner.nextBigInteger());
System.out.println(
"Bill #" + n + " costs " + sum + ": each friend should pay " + sum.divide(bb) + "\n");
n++;
}
}
