import java.util.Scanner;

/*
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*/

/**
*
* @author sara
*/
public class sumrargham {
public static void main(String[] args) {
Scanner sara = new Scanner(System.in);
int n=sara.nextInt();
int sum=0;
while(n!=0){
sum+= n%10;
n/=10;

}
System.out.println("sum = "+sum);
}

}