#include <iostream>
#include <string.h>
#include <stdlib.h>

using namespace std;

int main() {
	char buffer[100] = "\0";
	cin >> buffer;
	int answer = 0;
	for (auto i = 0; i != ::strlen(buffer); ++i) {
		if ('0' <= buffer[i] && buffer[i] <= '9') {
			answer += buffer[i] - '0';
		}
	}
	cout << answer << endl;
	return 0;
}