import java.util.*;
 
public class Main {
  public static void main (String args[]) {
    Scanner sc = new Scanner(System.in);
    
    int abc = sc.nextInt();
    int a = abc/100;
    int b = (abc-a*100)/10;
    int c = (abc-a*100-b*10)/1;
    
    System.out.println(a+b+c);
  }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz