#include <iostream>
#include <cctype>

using namespace std;

int main()
{
	string S;
	cin >> S;
	int sum = 0;
	int i = 0;
	for( i = 0; i < S.size(); i++ ) {
		if( isdigit( S.at(i) ) ) {
			sum +=  S.at(i) - '0';
		}
	}
	cout << sum << endl;
	return 0;
}