#include <iostream>
#include <string>
#include <cctype>

using namespace std;

int main() {
  int sum=0, tmp;
  string str;

  cin >> str;

  for(int i=0;i<str.size();i++){
    if(isdigit(static_cast<unsigned char>(str[i]))){
      tmp = (int)(str[i] - '0');
      sum = sum + tmp;
    }
  }

  cout << sum << endl;
  return 0;
}