import java.util.Scanner;
public class Main{
public static void main(String[] args) {
Scanner sc= new Scanner(System.in);
int sum=0;
int n=sc.nextInt();
String str=sc.next();
for(int i=0; i<n; i++){
sum+=str.charAt(i)-'0';
//sum+=Character.getNumericValue(str.charAt(i));
}
System.out.println(sum);
}
}
1. charAt() - '0'
2.Character 클래스의 내장 함수 Character.getNumericValue(ch) 사용