#include <iostream>
#include <ostream>
#include <string>
using namespace std;

int main() {
    long long n, len;
    int S = 0;
    cin >> n;
    n=llabs(n);
    std::string str = std::to_string(n);
    len = str.size();
    for (int i = 0; i < len; i++) {
        S += str[i] - '0';
    }
    cout << S << endl;
    return 0;
}