#include <bits/stdc++.h>
using namespace std;
string s;
int main() {
	cin >> s;
	int ret = 0;
	for(int i = 0; i < s.size(); i++) {
		if(isdigit(s[i])) ret += s[i] - 48;
	}
	cout << ret << endl;
	return 0;
}