#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <stack>
#include <algorithm>
#include <string>
#include <map>
#include <iterator>
#include <set>
#include <queue>

using namespace std;


int main() {


    string S;
    cin >> S;
    int result = 0;
    for (int i = 0; i < S.size(); ++i) {
        if ((S[i] - '0') < 10) {
            result += (S[i]-'0');
        }
    }

    cout << result << endl;
    return 0;
}