#include <iostream>
#include <cstdlib>
#include <vector>
#include <algorithm>
int main()
{
    std::string s;
    std::cin >> s;
    int sum = 0;
    for(auto si = s.begin(); si != s.end(); si++){
        char c = *si;
        unsigned int i = c;
        if(49 <= i && i <= 57){
            sum += (i - 48);
        }
    }
    std::cout << sum;
    return 0;
}