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

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