#include <stdio.h>

int main()
{
	int sum = 0;
	char S[10001];
	scanf("%s", S);
	for (int i = 0; S[i] != '\0'; i++)
	{
		if (S[i] >= '1' && S[i] <= '9')
			sum += S[i] - '0';
	}
	printf("%d\n", sum);
	return 0;
}