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

int main()
{
	string S;
	cin >> S;
	int a=0;
	for (int i = 0; i < S.size(); ++i)
	{
		if (isdigit(S[i]))
			a += S[i] - '0';
	}
	cout << a << endl;

	return 0;
}