#include <iostream>
#include <string>
#include <algorithm>

int main() {
    std::string s;
    std::cin>>s;

    s.erase(std::remove_if(std::begin(s), std::end(s), [](char c)->bool {return !std::isdigit(c);}), std::end(s));
    
    int n=0;
    for(char c : s) {
        n += (c - '0');
    }
    std::cout<<n<<std::endl;
}