#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(), (x).end()
using ll = long long;

int main() {
    string s;
    cin >> s;
    int cnt = 0;
    for (auto c : s) {
        if (isdigit(c)) cnt += c - '0';
    }
    cout << cnt << endl;
    return 0;
}