public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int range = Integer.parseInt(sc.nextLine());
String input = sc.nextLine();
if (range <= 100) {
int sum = 0;
for (int i = 0; i < input.length(); i++) {
sum += (input.charAt(i) - '0');
}
System.out.println(sum);
}
}