#include <stdio.h>

int main()
{
	int sum = 0;
	char S[10001];
	scanf("%s", S);
	for (int i = 0; S[i] != '\0' && i < 10001; i++)
	{
		switch (S[i])
		{
		case '1':
			sum++;
			break;
		case '2':
			sum += 2;
			break;
		case '3':
			sum += 3;
			break;
		case '4':
			sum += 4;
			break;
		case '5':
			sum += 5;
			break;
		case '6':
			sum += 6;
			break;
		case '7':
			sum += 7;
			break;
		case '8':
			sum += 8;
			break;
		case '9':
			sum += 9;
			break;
		default:
			break;
		}
	}
	printf("%d\n", sum);
	return 0;
}