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

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