#include <cctype>
#include <iostream>

int main(int argc, char *argv[]) {
	std::string input;
	std::cin >> input;

	int answer = 0;
	for (auto i = input.begin(); i != input.end(); i++) {
		unsigned char current = static_cast<unsigned char>(*i);
		if (std::isdigit(current)) {
			answer += current - '0';
		}
	}
	std::cout << answer << std::endl;
	return 0;
}