#include <iostream>
#include <vector>
#include <algorithm>
#include <string>

#define REP(i, a, b) for (int i = int(a); i < int(b); i++)

using namespace std;

typedef long long int lli;

int main() {
    string s;
    cin >> s;
    int sum = 0;
    REP (i, 0, s.size()) {
        if ('0' <= s[i] && s[i] <= '9') sum += s[i] - '0';
    }
    cout << sum << endl;
    return 0;
}