#include <iostream>
#include <string>

using namespace std;

bool isdigit(char c) {
  return c >= '0' && c <= '9';
}

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