#include <bits/stdc++.h>

using namespace std;

int main(void) {
  string s;
  cin >> s;

  int ans = 0;
  for (int i = 0; i < s.size(); i++) {
    if (!isdigit(s[i])) continue;
    ans += s[i] - '0';
  }

  cout << ans << endl;

  return 0;
}