#include<iostream>
#include<string>

using namespace std;

int main() {

	std::string s;

	cin >> s;

	int i = -1;
	int sum = 0;
	int number = 0;

	while (s[++i]) {
		number = s[i];
		if (number >= '0' && number <= '9')sum += number - '0';
	}

	cout << sum;

	return 0;
}