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

int main() {
	string s;cin>>s;
	int ans=0;
	for(int i=0;i<s.size();i++){
		if(s[i]>=48 && s[i] <= 57)ans+=s[i]-'0';
	}
	cout<<ans<<endl;
	return 0;
}