#define _GLIBCXX_DEBUG
#define ll long long
#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

void print(auto a){
  cout << a;
}

void printL(auto a){
  cout << a << endl;
}

int C(char c){
  if(!('0' <= c and c <= '9')) return 0;
  return c-'0';
}

int main(){
  string S; cin >> S;
  int ans = 0;
  for(int i = 0; i < (int)S.size(); i++){
    ans += C(S[i]);
  }
  printL(ans);
}