#include <algorithm>
#include <iostream>
#include <iomanip>
#include <climits>
#include <string>
#include <vector>
#include <cmath>
#include <set>
#include <map>
using namespace std;
using ll = long long;

int main(void)
{
  string N;
  cin >> N;
  int Result = 0;
  for (int i = 0; i < N.size(); i++)
  {
    int temp = N.at(i) - 48;
    if (0 <= temp && temp <= 9)
    {
      Result += temp;
    }
  }
  cout << Result << endl;
  return 0;
}