#include <iostream>
#include <string>
using namespace std;

int main()
{

	string str;
	int total=0;

	cin >> str;

	for (int i = 0; i < str.size(); i++)
	{
		if (isdigit(str[i]))
		{
			total += str[i]-'0';
		}
	}

	cout << total << endl;

	return 0;
}