#include <iostream>
#include <string>


int main() {
    std::string s;
    std::cin >> s;
    int result = 0;
    for (int i = 0; i < s.size(); i++) {
        if (isdigit(s.at(i))) {
            result += s.at(i) - '0';
        }
    }
    std::cout << result << std::endl;
}