#include <iostream>
//#include <numeric>
//#include <vector>
//#include <cstdint>
#include <string>
#include <cstdlib>
using namespace std;

int main() {
	//char* array;
	//cin >> array;

	string s;
	cin >> s;

	int n = 0;

	for (int i = 0; i < s.length(); i++) {
		string a{ s[i] };
		n += atoi(a.c_str());
	}

	cout << n;


	return 0;

}