#include <iostream>
#include <string>
using namespace std;
int main() {
    string s;
    int i, an = 0;
    cin >> s;
    for (i = 0; i < s.length(); i++) {
        if (s[i] - '0' < 10) {an += s[i] - '0';}
    }
    cout << an << endl;
    return 0;
}