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

int main(){
	string s;
	cin >> s;
	
	int ans = 0;
	for( int i = 0; i < s.length(); i++ ){
		if( s[i] <= '9' )
			ans += s[i] - '0';
	}
	cout << ans << endl;
	return 0;
}