https://www.acmicpc.net/problem/11720
import java.util.*;
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int N = sc.nextInt();
String num = sc.next();
int sum = 0;
for (int i = 0; i < N; i++) {
sum += (num.charAt(i) - '0');
}
System.out.println(sum);
}
}