#include <stdio.h>

int main(void)
{
	char str[100];
	int i;
	int count = 0;
	scanf("%s", str);
	


	for (i = 0; str[i] != '\0'; i++) {
		if (str[i] <= '9') 
			count += (str[i] - 48);
	}

	printf("%d\n", count);

	return 0;
}