#include <iostream>
#include <cstdio>
#include <string>
#include <cctype>

using namespace std;

int main() {
	string s;
	int sum = 0;

	cin >> s;
	int n = s.size();

	for (int i = 0; i < n; i++) {
		if (isdigit(s[i])) {
			sum += s[i] - '0';
		}
	}
	cout << sum << endl;
	return 0;
}