#include <iostream>
#include <string>
using namespace std;

int main() {
  string str;
  int ans = 0;
  cin >> str;
  for (int i = 0; i < str.length(); i++) {
    if (isdigit(str[i])) {
      ans += str[i] - '0';
    }
  }
  cout << ans << endl;
}