#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <stdio.h>
#include <string.h>
#include <math.h>
using namespace std;

int main() {
    string s;
    cin >> s;
    
    int r = 0;
    int n = (int)s.size();
    for (int i = 0; i < n; i++) {
        int k = s[i] - '0';
        if (0 <= k && k < 10) r += k;
    }

    cout << r << endl;

    return 0;
}