#include <iostream>
using namespace std;

int main() {
	char s[10005];
		int sum=0,i;
	cin >> s;
	for (i = 0; s[i] != 0; i++) {
		switch (s[i]) {
		case '1':
			sum += 1; break;
		case '2':
			sum += 2; break;
		case '3':
			sum += 3; break;
		case '4':
			sum += 4; break;
		case '5':
			sum += 5; break;
		case '6':
			sum += 6; break;
		case '7':
			sum += 7; break;
		case '8':
			sum += 8; break;
		case '9':
			sum += 9; break;
		}
	}
	cout << sum<<"\n";
	return 0;
}