#include <iostream>
#include <vector>
#include <cmath>
#include <string>
using ll = long long;
using namespace std;
int main()
{
	string s;
	cin >> s;
	int r = 0;
	for (char c : s) {
		if (isdigit(c)) {
			r += (c - '0');
		}
	}
	cout << r << endl;
}