#include <bits/stdc++.h>

using namespace std;

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