#include <stdio.h>
#include <stdlib.h>

int main()
{
	char str[10000] = "";
	int ans = 0;
	scanf("%s", str, sizeof(str));

	for (int i = 0;str[i] != '\0';i++)
	{
		if (str[i] == '1')
		{
			ans += 1;
		}
		else if (str[i] == '2')
		{
			ans += 2;
		}
		else if (str[i] == '3')
		{
			ans += 3;
		}
		else if (str[i] == '4')
		{
			ans += 4;
		}
		else if (str[i] == '5')
		{
			ans += 5;
		}
		else if (str[i] == '6')
		{
			ans += 6;
		}
		else if (str[i] == '7')
		{
			ans += 7;
		}
		else if (str[i] == '8')
		{
			ans += 8;
		}
		else if (str[i] == '9')
		{
			ans += 9;
		}
	}

	printf("%d", ans);

	return 0;
}