#include <iostream>
#include <string>
int main() {
	std::string buffer;
	std::cin >> buffer;
	int answer(0);
	for (const auto& e : buffer) {
		if ('0' <= e&&e <= '9') {
			answer += e - '0';
		}
	}
	std::cout << answer << std::endl;
	return 0;
}