#include <iostream>

using namespace std;

int main()
{
  char* str;
  cin >> str;
  int sum = 0;
  for (int i = 0; str[i] != '\0'; i++) {
    if ('1' <= str[i] && str[i] <= '9') { sum += str[i] - '0'; }
  }
  cout << sum << endl;
  return 0;
}