import java.util.Scanner;
class NewClass {
public static int sumofDigits(int n){
int sum=0;
while(n!=0){
int remainder = n % 10;
sum += remainder ;
n=n/10;
}
return sum;
}
public static void main(String args[] ) throws Exception {
Scanner scanner=new Scanner(System.in);
int n=scanner.nextInt();
System.out.println("sum of digits : "+sumofDigits(n));
}
}