#include <bits/stdc++.h>
using namespace std;
int main(){
  string S;
  cin >> S;
  int N = S.size();
  int ans = 0;
  for (int i = 0; i < N; i++){
    if (isdigit(S[i])){
      ans += S[i] - '0';
    }
  }
  cout << ans << endl;
}