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

int main(int argc, char**argv)
{
	string s; cin >> s;
	int total = 0;
	for (int ii=0; ii<s.size(); ++ii) {
		total += atoi(s.substr(ii, 1).c_str());
	}
	cout << total << endl;
	return 0;
}