#include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for (int i = 0; i < (n); i++)
typedef long long ll;
// Welcome to my source code!

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