#include <iostream>
#include <algorithm>
using namespace std;
 
int main(){
	string S;
	cin >> S;
	int ans = 0;
	for(int i = 0; i < S.size(); i++){
		if(S[i] <= '9'){
			ans += S[i] - '0';
		}
	}
	cout << ans << endl;
}