#include <iostream>
#include <string>

int main() {
    std::string s;
    int ans = 0;
    
    std::cin >> s;
    
    for (int i = 0; i < s.size(); i++) {
        if (s[i] >= 48 && s[i] <= 57) ans += (s[i] - 48);
    } 
    
    std::cout << ans << std::endl;
	
	return 0;
}