#include <iostream>
#include <string>

using namespace std;

int main(int argc, char const* argv[]) {
    string input_word;
    int total = 0;

    cin >> input_word;

    for (int i = 0; i < input_word.size(); i++) {
        if (isdigit(input_word[i])) {
            total += input_word[i] - '0';
        }
    }

    cout << total << endl;
    return 0;
}